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of account compromise attacks included malicious mail rules",{"items":230},[231],{"fullName":232,"firstName":233,"jobTitle":234,"profilePicture":235},"Sally Soulliere","Sally","Head of Brand & Content",{"url":236},"https://images.ctfassets.net/y1cdw1ablpvd/7Gh4SbbEj6Zsbd6OzGto8Q/885041a4ddeccc5ef3045c0e22975ef4/T016S22KZ96-U036FPETQRH-330f87708d26-192.jpeg",{"json":238,"links":673},{"nodeType":239,"data":240,"content":241},"document",{},[242,266,273,280,359,366,474,496,504,511,518,525,532,539,558,565,572,579,587,594,617,624,631,638,645,652],{"nodeType":243,"data":244,"content":245},"paragraph",{},[246,251,262],{"nodeType":247,"value":248,"marks":249,"data":250},"text","In a ",[],{},{"nodeType":252,"data":253,"content":255},"hyperlink",{"uri":254},"https://expel.com/expel-quarterly-threat-report/",[256],{"nodeType":247,"value":257,"marks":258,"data":261},"new report from Expel",[259],{"type":260},"underline",{},{"nodeType":247,"value":263,"marks":264,"data":265},", the managed detection and response (MDR) vendor found that of all the incidents detected in their SOC, 56% were account compromise and account takeover. Perhaps most surprising, though, is that in around half of those incidents, Expel’s SOC analysts found attackers had created new inbox rules to delete or hide emails that could give them away. Essentially, it’s a living off the land (LOTL) detection evasion technique hackers use to cover their tracks during a Business Email Compromise (BEC) attack.",[],{},{"nodeType":243,"data":267,"content":268},{},[269],{"nodeType":247,"value":270,"marks":271,"data":272},"At Push, we dub those attacker-created email rules “malicious mail rules,” and they’re not only useful for hiding attacks. They can also be used to exfiltrate sensitive data and as a way to get persistent access to victim accounts. ",[],{},{"nodeType":243,"data":274,"content":275},{},[276],{"nodeType":247,"value":277,"marks":278,"data":279},"There are a few different ways that an attacker can compromise an email account and set up malicious mail rules.:",[],{},{"nodeType":281,"data":282,"content":283},"ordered-list",{},[284,301,316,331],{"nodeType":285,"data":286,"content":287},"list-item",{},[288],{"nodeType":243,"data":289,"content":290},{},[291,297],{"nodeType":247,"value":292,"marks":293,"data":296},"Phishing attack",[294],{"type":295},"bold",{},{"nodeType":247,"value":298,"marks":299,"data":300},": The attacker tricks their victim into giving them their email account credentials.",[],{},{"nodeType":285,"data":302,"content":303},{},[304],{"nodeType":243,"data":305,"content":306},{},[307,312],{"nodeType":247,"value":308,"marks":309,"data":311},"Credential stuffing attack",[310],{"type":295},{},{"nodeType":247,"value":313,"marks":314,"data":315},": The attacker uses credentials that have already been compromised, possibly from another account that shares the same credentials as their email account.",[],{},{"nodeType":285,"data":317,"content":318},{},[319],{"nodeType":243,"data":320,"content":321},{},[322,327],{"nodeType":247,"value":323,"marks":324,"data":326},"Brute force attack",[325],{"type":295},{},{"nodeType":247,"value":328,"marks":329,"data":330},": The attacker breaks into the victim’s email account by trying common passwords and their known email username.",[],{},{"nodeType":285,"data":332,"content":333},{},[334],{"nodeType":243,"data":335,"content":336},{},[337,340,355],{"nodeType":247,"value":29,"marks":338,"data":339},[],{},{"nodeType":341,"data":342,"content":348},"entry-hyperlink",{"target":343},{"sys":344},{"id":345,"type":346,"linkType":347},"1bV8YTSQHvveCTnRc4H8su","Link","Entry",[349],{"nodeType":247,"value":350,"marks":351,"data":354},"Consent-phishing attack",[352,353],{"type":260},{"type":295},{},{"nodeType":247,"value":356,"marks":357,"data":358},": The attacker creates a malicious, but legit-looking, SaaS app, or compromises a genuine SaaS application. The victim consents (or has already consented) that application access to their data, including email, using OAuth 2.0 protocol.",[],{},{"nodeType":243,"data":360,"content":361},{},[362],{"nodeType":247,"value":363,"marks":364,"data":365},"Once the attacker has gained email access through either of the attacks above, they’ll create custom mail rules, which allow them to: ",[],{},{"nodeType":367,"data":368,"content":369},"unordered-list",{},[370,407,444,459],{"nodeType":285,"data":371,"content":372},{},[373,385],{"nodeType":243,"data":374,"content":375},{},[376,381],{"nodeType":247,"value":377,"marks":378,"data":380},"Forward and delete emails",[379],{"type":295},{},{"nodeType":247,"value":382,"marks":383,"data":384}," containing sensitive data from employee inboxes to their own: ",[],{},{"nodeType":367,"data":386,"content":387},{},[388],{"nodeType":285,"data":389,"content":390},{},[391],{"nodeType":243,"data":392,"content":393},{},[394,398,403],{"nodeType":247,"value":395,"marks":396,"data":397},"Usually attackers will forward emails matching sensitive keywords, like ‘invoice,’ ‘payment,’ or ‘confidential’ to an external email address controlled by the attacker. This is what happened during the ",[],{},{"nodeType":247,"value":399,"marks":400,"data":402},"SANS data breach in 2020",[401],{"type":260},{},{"nodeType":247,"value":404,"marks":405,"data":406},".",[],{},{"nodeType":285,"data":408,"content":409},{},[410],{"nodeType":243,"data":411,"content":412},{},[413,418,422,431,435,440],{"nodeType":247,"value":414,"marks":415,"data":417},"Delete important emails from particular senders",[416],{"type":295},{},{"nodeType":247,"value":419,"marks":420,"data":421},", as seen in this ",[],{},{"nodeType":252,"data":423,"content":425},{"uri":424},"https://www.reddit.com/r/sysadmin/comments/6l63x6/malicious_outlook_rules/",[426],{"nodeType":247,"value":427,"marks":428,"data":430},"Reddit thread",[429],{"type":260},{},{"nodeType":247,"value":432,"marks":433,"data":434},", so the ",[],{},{"nodeType":247,"value":436,"marks":437,"data":439},"attacker can masquerade as an executive",[438],{"type":295},{},{"nodeType":247,"value":441,"marks":442,"data":443}," at the company for social engineering purposes. Attackers will mark emails from impersonated executives as read and then delete them to improve their social engineering attack. That stops the victim from receiving genuine emails from those execs, which may arouse their suspicions and stop them from responding to the fake exec/attacker. ",[],{},{"nodeType":285,"data":445,"content":446},{},[447],{"nodeType":243,"data":448,"content":449},{},[450,455],{"nodeType":247,"value":451,"marks":452,"data":454},"Move laterally to other accounts",[453],{"type":295},{},{"nodeType":247,"value":456,"marks":457,"data":458},", by forwarding and deleting password reset emails to an attacker. This allows attackers to compromise and take over other accounts the victim has with other services. ",[],{},{"nodeType":285,"data":460,"content":461},{},[462],{"nodeType":243,"data":463,"content":464},{},[465,470],{"nodeType":247,"value":466,"marks":467,"data":469},"Monitor whether their attack has been detected ",[468],{"type":295},{},{"nodeType":247,"value":471,"marks":472,"data":473},"by forwarding emails that contain any language consistent with the investigation of a potential compromise.",[],{},{"nodeType":243,"data":475,"content":476},{},[477,481,492],{"nodeType":247,"value":478,"marks":479,"data":480},"We’ve written more about this ",[],{},{"nodeType":341,"data":482,"content":486},{"target":483},{"sys":484},{"id":485,"type":346,"linkType":347},"2zZ8kxP0t8Smi9b6hpT34k",[487],{"nodeType":247,"value":488,"marks":489,"data":491},"here",[490],{"type":260},{},{"nodeType":247,"value":493,"marks":494,"data":495},". As well as being stealthy, mail rules also give the attacker persistent access to data in their victim’s mailbox, even if they change their password, turn on MFA, or even completely rebuild their workstation.",[],{},{"nodeType":497,"data":498,"content":499},"heading-1",{},[500],{"nodeType":247,"value":501,"marks":502,"data":503},"How to detect suspicious mail rules",[],{},{"nodeType":243,"data":505,"content":506},{},[507],{"nodeType":247,"value":508,"marks":509,"data":510},"Since this is such a common and often-overlooked or hidden attack vector, it’s one of the first features we build into our product at Push. We knew from our time spent as incident responders that it’s a really reliable way to uncover account compromise.",[],{},{"nodeType":243,"data":512,"content":513},{},[514],{"nodeType":247,"value":515,"marks":516,"data":517},"In Push, whenever a new mail rule gets created, we detect it and automatically message the employee who owns the email account to ask whether they just created it. We do this via Slack or Teams and it’s one of our ChatOps messages with the highest and fastest response rates, because employees can instantly say “yes, it was me - I created that mail rule” or “No, I didn’t create it.” They don’t need to know a thing about security to respond to the prompt. ",[],{},{"nodeType":243,"data":519,"content":520},{},[521],{"nodeType":247,"value":522,"marks":523,"data":524},"If they say they don’t recognize it, we alert your security team and they can disable or delete the rule immediately in the alert. ",[],{},{"nodeType":526,"data":527,"content":531},"embedded-entry-block",{"target":528},{"sys":529},{"id":530,"type":346,"linkType":347},"6gkDIcWO5e9VX7QBVMt02w",[],{"nodeType":243,"data":533,"content":534},{},[535],{"nodeType":247,"value":536,"marks":537,"data":538},"Remember, creating malicious mail rules are a post-compromise activity and rarely the attacker’s sole objective, so you need to determine what else the attacker has gotten up to. They’re a reliable indicator of compromise (IoC) that should trigger an investigation to determine the scope of the incident and the steps necessary to eradicate the attacker from your environment. ",[],{},{"nodeType":243,"data":540,"content":541},{},[542,546,554],{"nodeType":247,"value":543,"marks":544,"data":545},"Use Push for free - ",[],{},{"nodeType":252,"data":547,"content":549},{"uri":548},"https://pushsecurity.com/sign-up",[550],{"nodeType":247,"value":551,"marks":552,"data":553},"sign up today",[],{},{"nodeType":247,"value":555,"marks":556,"data":557}," to start detecting suspicious mail rules that can indicate an ongoing attack. ",[],{},{"nodeType":497,"data":559,"content":560},{},[561],{"nodeType":247,"value":562,"marks":563,"data":564},"Shouldn’t I just disable mail rules to prevent these attacks from happening?",[],{},{"nodeType":243,"data":566,"content":567},{},[568],{"nodeType":247,"value":569,"marks":570,"data":571},"Short answer: No! They can be really useful.",[],{},{"nodeType":243,"data":573,"content":574},{},[575],{"nodeType":247,"value":576,"marks":577,"data":578},"Longer answer: Banning external auto-forwarding of email is too heavy-handed and employees who have legitimate business reasons for using the feature. ",[],{},{"nodeType":580,"data":581,"content":582},"heading-2",{},[583],{"nodeType":247,"value":584,"marks":585,"data":586},"Legitimate reasons for using mail rules…",[],{},{"nodeType":243,"data":588,"content":589},{},[590],{"nodeType":247,"value":591,"marks":592,"data":593},"Many companies/teams will outsource or automate certain processes by forwarding emails. A few common examples of this:",[],{},{"nodeType":367,"data":595,"content":596},{},[597,607],{"nodeType":285,"data":598,"content":599},{},[600],{"nodeType":243,"data":601,"content":602},{},[603],{"nodeType":247,"value":604,"marks":605,"data":606},"Some tools and SaaS apps don't allow you to set a billing email. So the user that signs up and pays receives the receipt, but needs to get that over to their accounts payable contact.",[],{},{"nodeType":285,"data":608,"content":609},{},[610],{"nodeType":243,"data":611,"content":612},{},[613],{"nodeType":247,"value":614,"marks":615,"data":616},"Many finance and billing apps and tools provide customers with a random email address (on their domain) to forward receipts to, which employees use for expenses",[],{},{"nodeType":580,"data":618,"content":619},{},[620],{"nodeType":247,"value":621,"marks":622,"data":623},"A bit less clear…",[],{},{"nodeType":243,"data":625,"content":626},{},[627],{"nodeType":247,"value":628,"marks":629,"data":630},"A use case that’s in a bit more of a grey area is when you’re working with contractors. Some security-minded companies will provide a company email address to the contractor to prevent them from having to worry about the security of the individual contractor’s email service. Contractors, however, may not want to be checking their corporate email when they’re working with many other companies and having to check separate company email accounts, Slack messages, and so on, so they’ll set up a forwarding rule so they have visibility of all of their contract work in a single email inbox and only use the official corporate email if they need to send an email to that company’s internal team.  ",[],{},{"nodeType":243,"data":632,"content":633},{},[634],{"nodeType":247,"value":635,"marks":636,"data":637},"That particular use case is clearly problematic from a security perspective, but you’ll need to find the balance between keeping the company secure and not overly-restricting employees (or contractors) from getting their work done. There’s no clear right answer for that one.",[],{},{"nodeType":580,"data":639,"content":640},{},[641],{"nodeType":247,"value":642,"marks":643,"data":644},"Limit, but don’t restrict completely",[],{},{"nodeType":243,"data":646,"content":647},{},[648],{"nodeType":247,"value":649,"marks":650,"data":651},"In our opinion, you want to limit the risk without blocking employees and becoming, once again, the dreaded “Department of No.” ",[],{},{"nodeType":243,"data":653,"content":654},{},[655,659,669],{"nodeType":247,"value":656,"marks":657,"data":658},"We’ve provided a lot of practical options for how to limit the risks mail rules present ",[],{},{"nodeType":341,"data":660,"content":664},{"target":661},{"sys":662},{"id":663,"type":346,"linkType":347},"roVnr9Z2sHDPGtemZUE7u",[665],{"nodeType":247,"value":488,"marks":666,"data":668},[667],{"type":260},{},{"nodeType":247,"value":670,"marks":671,"data":672},", including how to manage this risk manually via Google Workspace and Microsoft 365. Of course, we'll also explain how Push can automate these processes for you.",[],{},{"entries":674},{"inline":675,"hyperlink":676,"block":690},[],[677,682,686],{"sys":678,"__typename":679,"title":680,"slug":681},{"id":345},"BlogPosts","Consent phishing: the emerging phishing technique that can bypass 2FA","consent-phishing-the-emerging-phishing-technique-that-can-bypass-2fa",{"sys":683,"__typename":679,"title":684,"slug":685},{"id":485},"Email security: How hackers use mail rules to access your inbox","email-security-how-hackers-use-mail-rules-to-access-your-inbox",{"sys":687,"__typename":679,"title":688,"slug":689},{"id":663},"Should you disable external email auto-forwarding?","should-you-disable-external-email-auto-forwarding",[691],{"sys":692,"__typename":693,"title":694,"caption":695,"layoutMode":696,"file":697},{"id":530},"Image","Malicious mail rule channel chatops","Example of a Security team channel notification after an employee confirmed they did not create a suspicious mail rule","Centre aligned",{"url":698,"width":699,"height":700},"https://images.ctfassets.net/y1cdw1ablpvd/7Di3p6XTcrrW72VihrWcgm/18636a9977fc63bc3e07c95c6b3ee681/Screenshot_2023-06-02_at_14.33.20__1_.png",950,590,"json",{"items":703},[],{},"Account compromise attacks: 50% include malicious mail rules","2023-06-06T00:00:00.000Z",{"items":708},[709,1087,1423],{"__typename":679,"sys":710,"content":711,"title":684,"synopsis":1060,"hashTags":1061,"publishedDate":1068,"slug":685,"tagsCollection":1069,"authorsCollection":1079},{"id":485},{"json":712},{"nodeType":239,"data":713,"content":714},{},[715,722,728,735,755,784,791,875,894,898,905,923,930,937,940,947,993,1000,1017,1024,1027,1035,1042],{"nodeType":243,"data":716,"content":717},{},[718],{"nodeType":247,"value":719,"marks":720,"data":721},"Mail rules are a handy feature found in most email clients. You might have used them to forward emails to your teammates while you’re off sipping Piña coladas, or to move incoming email from that spammy colleague to the ‘don’t read’ folder.",[],{},{"nodeType":526,"data":723,"content":727},{"target":724},{"sys":725},{"id":726,"type":346,"linkType":347},"7xLVXoCCjansV1u50e2pbM",[],{"nodeType":243,"data":729,"content":730},{},[731],{"nodeType":247,"value":732,"marks":733,"data":734},"Sadly for us defenders, they’re just as useful for attackers. After gaining access to a victim's account, attackers will often create a mail rule inside their mailbox as a way to maintain stealthy access. This mail rule can do anything a normal mail rule could but is usually used to forward emails matching sensitive keywords, like ‘invoice’ or ‘payment’, to an external email address controlled by the attacker.",[],{},{"nodeType":736,"data":737,"content":738},"blockquote",{},[739],{"nodeType":243,"data":740,"content":741},{},[742,746,751],{"nodeType":247,"value":743,"marks":744,"data":745},"This gives the ",[],{},{"nodeType":247,"value":747,"marks":748,"data":750},"attacker persistent access to the mailbox",[749],{"type":295},{},{"nodeType":247,"value":752,"marks":753,"data":754},". Even if the victim's password is changed, they turn on MFA, or their workstation is completely rebuilt - as long as the rule stays in place, it remains effective.",[],{},{"nodeType":243,"data":756,"content":757},{},[758,762,770,774,780],{"nodeType":247,"value":759,"marks":760,"data":761},"As another example, in ",[],{},{"nodeType":252,"data":763,"content":764},{"uri":424},[765],{"nodeType":247,"value":766,"marks":767,"data":769},"this Reddit thread",[768],{"type":260},{},{"nodeType":247,"value":771,"marks":772,"data":773}," the author describes how mail rules were used to ",[],{},{"nodeType":247,"value":775,"marks":776,"data":779},"delete ",[777],{"type":778},"italic",{},{"nodeType":247,"value":781,"marks":782,"data":783},"any emails the affected user received from the company’s Chief Finance Officer (CFO) so that the attacker could pretend to be the CFO, sending them fake emails to convince them to transfer out company funds.",[],{},{"nodeType":243,"data":785,"content":786},{},[787],{"nodeType":247,"value":788,"marks":789,"data":790},"Business Email Compromise (BEC) like this is the most popular type of attack at the moment, causing damages well into the billions according to the FBI. Here are just a few publicly documented breaches involving mail rules:",[],{},{"nodeType":367,"data":792,"content":793},{},[794,814,834,855],{"nodeType":285,"data":795,"content":796},{},[797],{"nodeType":243,"data":798,"content":799},{},[800,803,811],{"nodeType":247,"value":29,"marks":801,"data":802},[],{},{"nodeType":252,"data":804,"content":806},{"uri":805},"https://www.sans.org/dataincident2020",[807],{"nodeType":247,"value":808,"marks":809,"data":810},"SANS: 28,000 PII records lost",[],{},{"nodeType":247,"value":29,"marks":812,"data":813},[],{},{"nodeType":285,"data":815,"content":816},{},[817],{"nodeType":243,"data":818,"content":819},{},[820,823,831],{"nodeType":247,"value":29,"marks":821,"data":822},[],{},{"nodeType":252,"data":824,"content":826},{"uri":825},"https://www.ic3.gov/Media/News/2020/201204.pdf",[827],{"nodeType":247,"value":828,"marks":829,"data":830},"FBI report: BEC involving malicious mail rules costs company $175k",[],{},{"nodeType":247,"value":29,"marks":832,"data":833},[],{},{"nodeType":285,"data":835,"content":836},{},[837],{"nodeType":243,"data":838,"content":839},{},[840,843,851],{"nodeType":247,"value":29,"marks":841,"data":842},[],{},{"nodeType":252,"data":844,"content":846},{"uri":845},"https://www.reddit.com/r/Office365/comments/ej0wkx/hacker_created_forwarding_rules_for_users_account/",[847],{"nodeType":247,"value":848,"marks":849,"data":850},"Reddit thread: Hacker created forwarding rule for user's account",[],{},{"nodeType":247,"value":852,"marks":853,"data":854}," ",[],{},{"nodeType":285,"data":856,"content":857},{},[858],{"nodeType":243,"data":859,"content":860},{},[861,864,872],{"nodeType":247,"value":29,"marks":862,"data":863},[],{},{"nodeType":252,"data":865,"content":867},{"uri":866},"https://www.microsoft.com/security/blog/2021/06/14/behind-the-scenes-of-business-email-compromise-using-cross-domain-threat-data-to-disrupt-a-large-bec-infrastructure/",[868],{"nodeType":247,"value":869,"marks":870,"data":871},"Microsoft case study of BEC operation using mail rules",[],{},{"nodeType":247,"value":29,"marks":873,"data":874},[],{},{"nodeType":243,"data":876,"content":877},{},[878,882,890],{"nodeType":247,"value":879,"marks":880,"data":881},"You can read ",[],{},{"nodeType":252,"data":883,"content":885},{"uri":884},"/blog/case-study-business-email-compromise-bec-attack-nearly-cost-us-millions/",[886],{"nodeType":247,"value":887,"marks":888,"data":889},"this case study",[],{},{"nodeType":247,"value":891,"marks":892,"data":893}," of a how a real Business Email Compromise (BEC) attack played out at an engineering firm that we interviewed.",[],{},{"nodeType":895,"data":896,"content":897},"hr",{},[],{"nodeType":497,"data":899,"content":900},{},[901],{"nodeType":247,"value":902,"marks":903,"data":904},"How likely is this to actually happen?",[],{},{"nodeType":243,"data":906,"content":907},{},[908,911,919],{"nodeType":247,"value":29,"marks":909,"data":910},[],{},{"nodeType":252,"data":912,"content":914},{"uri":913},"https://attack.mitre.org/techniques/T1114/003/",[915],{"nodeType":247,"value":916,"marks":917,"data":918},"MITRE lists threat groups",[],{},{"nodeType":247,"value":920,"marks":921,"data":922}," that have been known to use mail rules in this way as part of targeted attacks. However, most often, this technique is used opportunistically.",[],{},{"nodeType":243,"data":924,"content":925},{},[926],{"nodeType":247,"value":927,"marks":928,"data":929},"Attackers run phishing campaigns containing thousands of harvested emails from multiple companies. A classic scenario is to trick a user into logging in to a fake Office 365 or Google Workspace login screen, stealing their credentials. Those credentials are then used to create a malicious mail rule inside the compromised user's mailbox. For scale and speed, this process is completely automated.",[],{},{"nodeType":243,"data":931,"content":932},{},[933],{"nodeType":247,"value":934,"marks":935,"data":936},"Similarly a mail rule could be created automatically as the result of a user’s workstation becoming infected with malware.",[],{},{"nodeType":895,"data":938,"content":939},{},[],{"nodeType":497,"data":941,"content":942},{},[943],{"nodeType":247,"value":944,"marks":945,"data":946},"How to defend against this type of attack?",[],{},{"nodeType":243,"data":948,"content":949},{},[950,954,962,966,976,980,990],{"nodeType":247,"value":951,"marks":952,"data":953},"The first step is to check your mailboxes to make sure no malicious mail rules have already been created. On Office 365, this will require rolling some PowerShell; on Google Workspace, you'll need to query the APIs (we discuss some detail of these options ",[],{},{"nodeType":252,"data":955,"content":957},{"uri":956},"/blog/should-you-disable-external-email-auto-forwarding/",[958],{"nodeType":247,"value":959,"marks":960,"data":961},"in this post",[],{},{"nodeType":247,"value":963,"marks":964,"data":965},"). Or you can save yourself some pain and use the free tool linked above, which we built for this very purpose. If you find rules that don't look right, follow these guides for what to do next on ",[],{},{"nodeType":341,"data":967,"content":971},{"target":968},{"sys":969},{"id":970,"type":346,"linkType":347},"e4805bba-2531-4250-bdcc-ab996dd33519",[972],{"nodeType":247,"value":973,"marks":974,"data":975},"Office 365",[],{},{"nodeType":247,"value":977,"marks":978,"data":979}," or ",[],{},{"nodeType":341,"data":981,"content":985},{"target":982},{"sys":983},{"id":984,"type":346,"linkType":347},"50dab356-e78b-479d-ad45-a07b898b5ec4",[986],{"nodeType":247,"value":987,"marks":988,"data":989},"Google Workspace",[],{},{"nodeType":247,"value":404,"marks":991,"data":992},[],{},{"nodeType":243,"data":994,"content":995},{},[996],{"nodeType":247,"value":997,"marks":998,"data":999},"It's also possible to stop users from creating auto-forwarding rules altogether. If no one is using the feature, this is probably a good idea - you might as well reduce risk. However, there are plenty of situations where teams benefit from the automation and efficiency mail rules bring. Security works best when it enables the business to work securely, rather than constraining it - leaving the feature available whilst managing the risk through detection is a good option as well.",[],{},{"nodeType":243,"data":1001,"content":1002},{},[1003,1007,1014],{"nodeType":247,"value":1004,"marks":1005,"data":1006},"We discuss more about the pros and cons of disabling mail rules and some options for some security controls you can implement so that you can keep them enabled ",[],{},{"nodeType":252,"data":1008,"content":1009},{"uri":956},[1010],{"nodeType":247,"value":1011,"marks":1012,"data":1013},"in this blog post",[],{},{"nodeType":247,"value":404,"marks":1015,"data":1016},[],{},{"nodeType":243,"data":1018,"content":1019},{},[1020],{"nodeType":247,"value":1021,"marks":1022,"data":1023},"If you'd like, try Push for free and we'll spot any suspicious mail rules, then work with employees to make sure the mail rule wasn't something they created for a legitimate use. If they haven't, we'll notify you to take action and investigate a potential incident. Find out more here.",[],{},{"nodeType":895,"data":1025,"content":1026},{},[],{"nodeType":497,"data":1028,"content":1029},{},[1030],{"nodeType":247,"value":1031,"marks":1032,"data":1034},"Learn more",[1033],{"type":295},{},{"nodeType":243,"data":1036,"content":1037},{},[1038],{"nodeType":247,"value":1039,"marks":1040,"data":1041},"It doesn’t stop there — Push provides comprehensive identity attack detection and response capabilities against techniques like credential stuffing, password spraying and session hijacking using stolen session tokens. You can also use Push to find and fix identity vulnerabilities across every app that your employees use like: ghost logins; SSO coverage gaps; MFA gaps; weak, breached and reused passwords; risky OAuth integrations; and more. ",[],{},{"nodeType":243,"data":1043,"content":1044},{},[1045,1049,1057],{"nodeType":247,"value":1046,"marks":1047,"data":1048},"If you want to learn more about how Push helps you to detect and defeat common identity attack techniques, ",[],{},{"nodeType":252,"data":1050,"content":1052},{"uri":1051},"https://pushsecurity.com/demo?utm_campaign=12081956-FY25Q2_Hacker-News-Article&utm_source=thehackernews&utm_medium=sponsored&utm_content=external-article",[1053],{"nodeType":247,"value":1054,"marks":1055,"data":1056},"book some time with one of our team for a live demo",[],{},{"nodeType":247,"value":404,"marks":1058,"data":1059},[],{},"After phishing campaigns target Office 365 and Google Workspace users, malicious mail rules are automatically added to the user’s mailbox. Take steps to defend.",[1062,1063,1064,1065,1066,1067],"businessemailcompromise","bec","mailrules","office365","googleworkspace","emailsecurity","2021-06-10T00:00:00.000+01:00",{"items":1070},[1071,1075],{"sys":1072,"name":1074},{"id":1073},"6A5RXS31ZQx3PwryGb1IMy","Browser-based attacks",{"sys":1076,"name":1078},{"id":1077},"4ksQNCFeBf8H4QIORqpRLw","Detection & response",{"items":1080},[1081],{"fullName":1082,"firstName":1083,"jobTitle":1084,"profilePicture":1085},"Andy Waugh","Andy","VP Product",{"url":1086},"https://images.ctfassets.net/y1cdw1ablpvd/3Rf76rJn6S9inMb4dUnAIJ/0a787f8141d05b95300e2fe77c4493fa/DSC_6868.jpg",{"__typename":679,"sys":1088,"content":1089,"title":688,"synopsis":1410,"hashTags":1411,"publishedDate":1412,"slug":689,"tagsCollection":1413,"authorsCollection":1419},{"id":663},{"json":1090},{"data":1091,"content":1092,"nodeType":239},{},[1093,1112,1119,1148,1164,1171,1178,1185,1193,1200,1220,1227,1247,1253,1261,1268,1288,1296,1315,1323,1330,1383,1391,1398,1404],{"data":1094,"content":1095,"nodeType":243},{},[1096,1100,1108],{"data":1097,"marks":1098,"value":1099,"nodeType":247},{},[],"Mail rules can be abused by attackers to get stealthy, persistent access to a mailbox, leak data and facilitate high-impact Business Email Compromise (",{"data":1101,"content":1103,"nodeType":252},{"uri":1102},"/blog/email-security-how-hackers-use-mail-rules-to-access-your-inbox/",[1104],{"data":1105,"marks":1106,"value":1107,"nodeType":247},{},[],"read more here",{"data":1109,"marks":1110,"value":1111,"nodeType":247},{},[],"). So, lots of organisations decide to ban external auto-forwarding of email altogether. The question is, is this a good move?",{"data":1113,"content":1114,"nodeType":580},{},[1115],{"data":1116,"marks":1117,"value":1118,"nodeType":247},{},[],"This is damage limitation, not prevention",{"data":1120,"content":1121,"nodeType":243},{},[1122,1126,1131,1135,1144],{"data":1123,"marks":1124,"value":1125,"nodeType":247},{},[],"It’s important to recognise that adding a malicious mail rule to a user’s mailbox is a ",{"data":1127,"marks":1128,"value":1130,"nodeType":247},{},[1129],{"type":295},"post-compromise activity",{"data":1132,"marks":1133,"value":1134,"nodeType":247},{},[],". That is, an attacker has already compromised the victim somehow - compromised their password, deployed malware on their machine, performed consent phishing etc. - they already have access to their mailbox. At this point, you should assume all data in the mailbox is compromised anyway. (See here for “",{"data":1136,"content":1139,"nodeType":341},{"target":1137},{"sys":1138},{"id":970,"type":346,"linkType":347},[1140],{"data":1141,"marks":1142,"value":1143,"nodeType":247},{},[],"what to do if I find a malicious mail rule?",{"data":1145,"marks":1146,"value":1147,"nodeType":247},{},[],"”)",{"data":1149,"content":1150,"nodeType":243},{},[1151,1155,1160],{"data":1152,"marks":1153,"value":1154,"nodeType":247},{},[],"Preventing external auto-forwarding rules therefore reduces",{"data":1156,"marks":1157,"value":1159,"nodeType":247},{},[1158],{"type":295}," further potential impact",{"data":1161,"marks":1162,"value":1163,"nodeType":247},{},[]," to a compromised account - worth doing if no one is using the feature, but what if your users are?",{"data":1165,"content":1166,"nodeType":580},{},[1167],{"data":1168,"marks":1169,"value":1170,"nodeType":247},{},[],"Security vs. user experience",{"data":1172,"content":1173,"nodeType":243},{},[1174],{"data":1175,"marks":1176,"value":1177,"nodeType":247},{},[],"Good security should enable a business and its users to work securely rather than constrain it. Controls that restrict users’ productivity or are seen as a nuisance will be bypassed and although you might prevent a potential attack type, you’ll ultimately cause less secure behaviour from your users.",{"data":1179,"content":1180,"nodeType":243},{},[1181],{"data":1182,"marks":1183,"value":1184,"nodeType":247},{},[],"With that in mind, if external auto-forwarding of email is something your users need - and there are plenty of legitimate scenarios where this may be the case - you should be considering how to manage the risk, rather than eliminate it. The good news is this is totally doable. Equally, if none, or most of your users don’t need this feature, you should of course disable it to reduce your overall risk.",{"data":1186,"content":1187,"nodeType":243},{},[1188],{"data":1189,"marks":1190,"value":1192,"nodeType":247},{},[1191],{"type":295},"Managing the risk on Exchange Online for Microsoft 365 through detection alone",{"data":1194,"content":1195,"nodeType":243},{},[1196],{"data":1197,"marks":1198,"value":1199,"nodeType":247},{},[],"Managing the risk of external auto-forwarding email rules means making sure you’re alerted when one is created. ",{"data":1201,"content":1202,"nodeType":243},{},[1203,1207,1216],{"data":1204,"marks":1205,"value":1206,"nodeType":247},{},[],"If you’re using Exchange Online for Microsoft 365, ",{"data":1208,"content":1210,"nodeType":252},{"uri":1209},"https://protection.office.com/alertpolicies",[1211],{"data":1212,"marks":1213,"value":1215,"nodeType":247},{},[1214],{"type":260},"an informational alert policy",{"data":1217,"marks":1218,"value":1219,"nodeType":247},{},[]," - “Creation of forwarding/redirect rule” - can be enabled so alerts of this type of suspicious rules will be sent to tenant admins when they are created in future. ",{"data":1221,"content":1222,"nodeType":243},{},[1223],{"data":1224,"marks":1225,"value":1226,"nodeType":247},{},[],"/prod",{"data":1228,"content":1229,"nodeType":243},{},[1230,1234,1243],{"data":1231,"marks":1232,"value":1233,"nodeType":247},{},[],"The downside of this approach is it isn’t possible to look retrospectively (",{"data":1235,"content":1237,"nodeType":252},{"uri":1236},"https://gcits.com/knowledge-base/find-inbox-rules-forward-mail-externally-office-365-powershell/",[1238],{"data":1239,"marks":1240,"value":1242,"nodeType":247},{},[1241],{"type":260},"without using PowerShell",{"data":1244,"marks":1245,"value":1246,"nodeType":247},{},[],") so alerts will only fire on future creation of forwarding rules. Additionally, alerts also fire for internal forwarding rules which can generate a lot of noise when looking specifically for malicious rules. ",{"data":1248,"content":1252,"nodeType":526},{"target":1249},{"sys":1250},{"id":1251,"type":346,"linkType":347},"2aafjsTsqy7ljL5hh8c3MO",[],{"data":1254,"content":1255,"nodeType":243},{},[1256],{"data":1257,"marks":1258,"value":1260,"nodeType":247},{},[1259],{"type":295},"Managing the risk on Exchange Online for Microsoft 365  through detection & prevention",{"data":1262,"content":1263,"nodeType":243},{},[1264],{"data":1265,"marks":1266,"value":1267,"nodeType":247},{},[],"In addition to being alerted when rules are created, you can take steps to either disallow external auto-forwarding rules altogether, or prevent them taking effect. You might think disallowing their creation is better but if you can permit creation but stop them from taking effect, you keep a high-fidelity detection of account compromise, without adding any additional risk.",{"data":1269,"content":1270,"nodeType":243},{},[1271,1275,1284],{"data":1272,"marks":1273,"value":1274,"nodeType":247},{},[],"In Exchange Online for Microsoft 365, you can achieve this with ",{"data":1276,"content":1278,"nodeType":252},{"uri":1277},"https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/external-email-forwarding?view=o365-worldwide",[1279],{"data":1280,"marks":1281,"value":1283,"nodeType":247},{},[1282],{"type":260},"outbound spam filter policies",{"data":1285,"marks":1286,"value":1287,"nodeType":247},{},[]," to automatically stop any emails auto-forwarded out of your organisation. If an attacker creates a malicious auto-forwarding rule, any forwarded mail will be blocked by the spam filter; if you have your alerts set up correctly, you’ll still receive an alert about the new malicious rule.",{"data":1289,"content":1290,"nodeType":243},{},[1291],{"data":1292,"marks":1293,"value":1295,"nodeType":247},{},[1294],{"type":295},"Managing the risk on Gmail for Google Workspace",{"data":1297,"content":1298,"nodeType":243},{},[1299,1303,1312],{"data":1300,"marks":1301,"value":1302,"nodeType":247},{},[],"Google Workspace only allows complete prevention, such that your users (and attackers) are not able to create forwarding settings. If you decide that is right for you, you can disable automatic forwarding entirely by ",{"data":1304,"content":1306,"nodeType":252},{"uri":1305},"https://support.google.com/a/answer/2491924?hl=en",[1307],{"data":1308,"marks":1309,"value":1311,"nodeType":247},{},[1310],{"type":260},"following these instructions",{"data":1313,"marks":1314,"value":404,"nodeType":247},{},[],{"data":1316,"content":1317,"nodeType":243},{},[1318],{"data":1319,"marks":1320,"value":1322,"nodeType":247},{},[1321],{"type":295},"Managing the risk using the Push platform",{"data":1324,"content":1325,"nodeType":243},{},[1326],{"data":1327,"marks":1328,"value":1329,"nodeType":247},{},[],"Using the Push platform makes managing this risk a lot easier with less of your time:",{"data":1331,"content":1332,"nodeType":367},{},[1333,1343,1353,1363,1373],{"data":1334,"content":1335,"nodeType":285},{},[1336],{"data":1337,"content":1338,"nodeType":243},{},[1339],{"data":1340,"marks":1341,"value":1342,"nodeType":247},{},[],"Connect your platform with a few clicks and we’ll sweep your estate for any suspicious rules currently in place.",{"data":1344,"content":1345,"nodeType":285},{},[1346],{"data":1347,"content":1348,"nodeType":243},{},[1349],{"data":1350,"marks":1351,"value":1352,"nodeType":247},{},[],"Get alerts via email or ChatOps (Slack or Teams) when new rules are created. Triage and deal with them directly from the email or chat platform.",{"data":1354,"content":1355,"nodeType":285},{},[1356],{"data":1357,"content":1358,"nodeType":243},{},[1359],{"data":1360,"marks":1361,"value":1362,"nodeType":247},{},[],"Use our ChatOps features to ask users directly if they recognise a rule when you’re unsure. You can even automate this so user feedback is already collected by the time you come to triage.",{"data":1364,"content":1365,"nodeType":285},{},[1366],{"data":1367,"content":1368,"nodeType":243},{},[1369],{"data":1370,"marks":1371,"value":1372,"nodeType":247},{},[],"Disable rules directly from the platform for quick response.",{"data":1374,"content":1375,"nodeType":285},{},[1376],{"data":1377,"content":1378,"nodeType":243},{},[1379],{"data":1380,"marks":1381,"value":1382,"nodeType":247},{},[],"Follow our detailed and clear guides for how to respond comprehensively.",{"data":1384,"content":1385,"nodeType":243},{},[1386],{"data":1387,"marks":1388,"value":1390,"nodeType":247},{},[1389],{"type":295},"Conclusion",{"data":1392,"content":1393,"nodeType":243},{},[1394],{"data":1395,"marks":1396,"value":1397,"nodeType":247},{},[],"If your users don’t use external email auto-forwarding, it makes sense to prevent the feature to limit the impact of a malicious mail rule. However, if there are legitimate business reasons for keeping the feature active, this risk can be sufficiently managed through detection.",{"data":1399,"content":1403,"nodeType":526},{"target":1400},{"sys":1401},{"id":1402,"type":346,"linkType":347},"2y0INxqAi594O7rCAVKhTI",[],{"data":1405,"content":1406,"nodeType":243},{},[1407],{"data":1408,"marks":1409,"value":29,"nodeType":247},{},[],"External email auto-forwarding is a feature but also a risk; learn whether you should disable it, and, if you can't, how to manage the risk through detection.",[1062,1063,1064,1065,1066],"2021-06-03T00:00:00.000+01:00",{"items":1414},[1415,1417],{"sys":1416,"name":1074},{"id":1073},{"sys":1418,"name":1078},{"id":1077},{"items":1420},[1421],{"fullName":1082,"firstName":1083,"jobTitle":1084,"profilePicture":1422},{"url":1086},{"__typename":679,"sys":1424,"content":1426,"title":1892,"synopsis":1893,"hashTags":62,"publishedDate":1894,"slug":1895,"tagsCollection":1896,"authorsCollection":1904},{"id":1425},"14NiRrBrLFVkR8h05RCD7F",{"json":1427},{"data":1428,"content":1429,"nodeType":239},{},[1430,1438,1446,1468,1476,1497,1504,1510,1517,1524,1531,1538,1545,1552,1559,1566,1573,1579,1586,1593,1600,1607,1627,1633,1640,1646,1653,1659,1666,1673,1680,1723,1730,1750,1757,1847,1867,1873,1880,1886],{"data":1431,"content":1432,"nodeType":243},{},[1433],{"data":1434,"marks":1435,"value":1437,"nodeType":247},{},[1436],{"type":778},"You get a call from your CFO: “Jenkins! ACME just called to find out why we haven’t paid invoices for the last 3 months? Didn’t you make payment last week?”",{"data":1439,"content":1440,"nodeType":243},{},[1441],{"data":1442,"marks":1443,"value":1445,"nodeType":247},{},[1444],{"type":778},"You think back a bit. “Yip! I received another invoice a few days ago and made payment yesterday. I also paid the contractor doing renovations on your house. By the way, congrats on the new kitchen.”",{"data":1447,"content":1448,"nodeType":243},{},[1449,1453,1464],{"data":1450,"marks":1451,"value":1452,"nodeType":247},{},[],"Many companies have had similar incidents occur over the last couple of years - it’s a classic ",{"data":1454,"content":1458,"nodeType":341},{"target":1455},{"sys":1456},{"id":1457,"type":346,"linkType":347},"pj2eLZXa4PyrY1DD4NCHt",[1459],{"data":1460,"marks":1461,"value":1463,"nodeType":247},{},[1462],{"type":260},"Business Email Compromise",{"data":1465,"marks":1466,"value":1467,"nodeType":247},{},[]," (BEC) scenario. An attacker managed to gain access to Jenkins in accounting’s email and intercepted email from legitimate creditors, replacing their banking details with the attacker's own, and even forging invoices from non-existent suppliers. Forged emails are then sent from the CEO or CFO to approve the payments.",{"data":1469,"content":1470,"nodeType":243},{},[1471],{"data":1472,"marks":1473,"value":1475,"nodeType":247},{},[1474],{"type":778},"But how did they manage to gain access to the account? Our security team enforced multi-factor authentication (MFA) a few weeks ago. We’re supposed to be secure!?",{"data":1477,"content":1478,"nodeType":243},{},[1479,1483,1493],{"data":1480,"marks":1481,"value":1482,"nodeType":247},{},[],"As detailed in our ",{"data":1484,"content":1487,"nodeType":341},{"target":1485},{"sys":1486},{"id":345,"type":346,"linkType":347},[1488],{"data":1489,"marks":1490,"value":1492,"nodeType":247},{},[1491],{"type":260},"blog post about consent phishing",{"data":1494,"marks":1495,"value":1496,"nodeType":247},{},[],", this attack method will bypass MFA, since the paired malicious third-party integration app (sometimes called OAuth) generates an authentication token. MFA checks are only applied when logging in with your username and password, so in this case, the attacker was able to get a valid access token into Jenkins’ account. ",{"data":1498,"content":1499,"nodeType":243},{},[1500],{"data":1501,"marks":1502,"value":1503,"nodeType":247},{},[],"While this isn’t necessarily the same level of access provided with a username/password combo, it might be, based on the scopes Jenkins granted the third-party integration app access to when they clicked ‘Accept’. ",{"data":1505,"content":1509,"nodeType":526},{"target":1506},{"sys":1507},{"id":1508,"type":346,"linkType":347},"5BIHqq49jJOHsEHLgc8Tb9",[],{"data":1511,"content":1512,"nodeType":243},{},[1513],{"data":1514,"marks":1515,"value":1516,"nodeType":247},{},[],"The list of third-party integration scopes can include anything from relatively benign things like retrieving your name, surname, and email address, to more dangerous or excessive permissions such as full access to your mailbox, the ability to configure mail rules to forward or delete email, and full access to your OneDrive or Sharepoint files. Worse case scenario: if you belong to groups with password reset capabilities, the attacker may be able to perform full account takeovers.",{"data":1518,"content":1519,"nodeType":580},{},[1520],{"data":1521,"marks":1522,"value":1523,"nodeType":247},{},[],"How do you detect and respond to such incidents?",{"data":1525,"content":1526,"nodeType":243},{},[1527],{"data":1528,"marks":1529,"value":1530,"nodeType":247},{},[],"The main issue is detection. In my experience as an incident responder working with Fortune 500 companies at MWR Infosecurity, I found that BEC attacks are usually detected when associated parties start asking questions about non-payment (or unrecognized payments), which can take weeks or months from the day of compromise. By this point your cloud provider’s logs are likely to have rolled over and you’re unlikely to find much useful information to populate your incident timeline.",{"data":1532,"content":1533,"nodeType":243},{},[1534],{"data":1535,"marks":1536,"value":1537,"nodeType":247},{},[],"Shameless plug alert: Push’s ChatOps functionality can greatly assist here as it detects such malicious rules when created, and sends a message to the owner of the account (Jenkins) asking if they created the rule. Sometimes a user will have a legitimate use for creating mail rules to forward messages to another account, and this allows them to acknowledge the rule and mark it as safe. In case they didn’t create it, they can flag it as such and this will cause an alert to be sent to their security team. This is practically instant detection and invaluable when preventing fraudulent payments. And getting input from the account owner cuts way down on alert fatigue for your team.",{"data":1539,"content":1540,"nodeType":580},{},[1541],{"data":1542,"marks":1543,"value":1544,"nodeType":247},{},[],"\nMitigate the attack \n",{"data":1546,"content":1547,"nodeType":243},{},[1548],{"data":1549,"marks":1550,"value":1551,"nodeType":247},{},[],"Once you’ve detected the incident, your next step is to remediate. Typically, this would require someone on the  security team to find the offending rule in your cloud provider’s control panel to disable it, which can take some time, depending on the team’s availability and other factors. ",{"data":1553,"content":1554,"nodeType":243},{},[1555],{"data":1556,"marks":1557,"value":1558,"nodeType":247},{},[],"Detecting the creation of malicious mail rules would require you to configure policies and alerts in your cloud provider’s control panel, and requires someone from the security team to monitor for notifications. If your IT person is also responsible for security in your organization, it’s unlikely that they would spend an appropriate amount of time looking at alerts and, in many cases, would need to follow up with employees to confirm if they had indeed created the rules. If you’re a larger organization, your dedicated security person will likely have higher priority tasks, too.",{"data":1560,"content":1561,"nodeType":243},{},[1562],{"data":1563,"marks":1564,"value":1565,"nodeType":247},{},[],"Discovering a breach is usually related to someone noticing unrecognized payments, vendors querying a lack of payments, or phishing emails being sent to fellow employees or contacts outside of your organization. If an attacker is careful to avoid causing too much interruption, then it’s likely that you won’t discover the breach until all the damage has been done. Usually by this point, performing an investigation will reveal very little due to important investigation artifacts disappearing due to logs rolling over.",{"data":1567,"content":1568,"nodeType":243},{},[1569],{"data":1570,"marks":1571,"value":1572,"nodeType":247},{},[],"If you’re using Push, we would automatically detect the mail rule, talk to the employee whose email the mail rule was created within, and if they didn’t set the mail rule up themselves, we would assume it was created by an attacker and alert your security team. Push’s ChatOps will disable the offending rule and mark it as suspicious.",{"data":1574,"content":1578,"nodeType":526},{"target":1575},{"sys":1576},{"id":1577,"type":346,"linkType":347},"6rV4EiwTgmBsmYEaUvv55b",[],{"data":1580,"content":1581,"nodeType":243},{},[1582],{"data":1583,"marks":1584,"value":1585,"nodeType":247},{},[],"If this were a typical credential compromise scenario, the account’s password would be reset and everyone would go about their lives. However, since no credentials were compromised in our example, you’d go onto the next step to…",{"data":1587,"content":1588,"nodeType":580},{},[1589],{"data":1590,"marks":1591,"value":1592,"nodeType":247},{},[],"Remove the app’s permissions and revoke the tokens",{"data":1594,"content":1595,"nodeType":243},{},[1596],{"data":1597,"marks":1598,"value":1599,"nodeType":247},{},[],"As I mentioned earlier, third-party integration apps generate tokens, which can be valid for an hour to sometimes 24 hours or more, depending on the integrating app, how it is being used, and if it makes use of refresh tokens.",{"data":1601,"content":1602,"nodeType":243},{},[1603],{"data":1604,"marks":1605,"value":1606,"nodeType":247},{},[],"Invalidating third-party integration access permissions requires accessing your cloud provider’s control panel. In this example, you need to revoke access for a malicious app in a Microsoft 365 tenant. Microsoft’s guidance on this is very useful, but unfortunately not as simple as just pressing a button.",{"data":1608,"content":1609,"nodeType":243},{},[1610,1614,1623],{"data":1611,"marks":1612,"value":1613,"nodeType":247},{},[],"To view Microsoft’s recommendations for dealing with a malicious app, you’d need to navigate to the ",{"data":1615,"content":1617,"nodeType":252},{"uri":1616},"https://portal.azure.com/#view/Microsoft_AAD_IAM/StartboardApplicationsMenuBlade/~/AppAppsPreview/menuId~/null",[1618],{"data":1619,"marks":1620,"value":1622,"nodeType":247},{},[1621],{"type":260},"Enterprise applications",{"data":1624,"marks":1625,"value":1626,"nodeType":247},{},[]," section in Azure, and locate the app by searching for its name or Application ID, which can be found in the Push app’s OAuth integrations page. In the app menu, click on ‘Permissions,’ then ‘Review permissions.’ ",{"data":1628,"content":1632,"nodeType":526},{"target":1629},{"sys":1630},{"id":1631,"type":346,"linkType":347},"5Z6T2anRIJ1he2phTbcFot",[],{"data":1634,"content":1635,"nodeType":243},{},[1636],{"data":1637,"marks":1638,"value":1639,"nodeType":247},{},[],"On the slide-out menu, select “This application is malicious and I’m compromised.”",{"data":1641,"content":1645,"nodeType":526},{"target":1642},{"sys":1643},{"id":1644,"type":346,"linkType":347},"2lGnKdKTjXAVYBiOtYrbEl",[],{"data":1647,"content":1648,"nodeType":243},{},[1649],{"data":1650,"marks":1651,"value":1652,"nodeType":247},{},[],"This will provide you with pre-generated PowerShell scripts to 1) Remove all users assigned to the application, 2) Revoke all permissions granted to the application, and 3) Revoke refresh tokens for all users.",{"data":1654,"content":1658,"nodeType":526},{"target":1655},{"sys":1656},{"id":1657,"type":346,"linkType":347},"3qdGQ12PdZFLEyIpmMkwPi",[],{"data":1660,"content":1661,"nodeType":580},{},[1662],{"data":1663,"marks":1664,"value":1665,"nodeType":247},{},[],"How to prevent similar attacks",{"data":1667,"content":1668,"nodeType":243},{},[1669],{"data":1670,"marks":1671,"value":1672,"nodeType":247},{},[],"A very important step following a compromise is to review what happened, how it happened, and what could be done to prevent the incident from occurring again. The interesting part about this incident is that it wasn’t due to a weak password, or even the lack of MFA that led to compromise. It came down to social engineering: instructing an employee to click a link by an account masquerading as their CFO.",{"data":1674,"content":1675,"nodeType":243},{},[1676],{"data":1677,"marks":1678,"value":1679,"nodeType":247},{},[],"For the purposes of this hypothetical incident, we’ll establish that the following occurred:",{"data":1681,"content":1682,"nodeType":367},{},[1683,1693,1703,1713],{"data":1684,"content":1685,"nodeType":285},{},[1686],{"data":1687,"content":1688,"nodeType":243},{},[1689],{"data":1690,"marks":1691,"value":1692,"nodeType":247},{},[],"Andrew Jenkins was targeted in a phishing attack",{"data":1694,"content":1695,"nodeType":285},{},[1696],{"data":1697,"content":1698,"nodeType":243},{},[1699],{"data":1700,"marks":1701,"value":1702,"nodeType":247},{},[],"Andrew authenticated via Microsoft 365, which is a legitimate and expected authentication mechanism and occurs almost daily",{"data":1704,"content":1705,"nodeType":285},{},[1706],{"data":1707,"content":1708,"nodeType":243},{},[1709],{"data":1710,"marks":1711,"value":1712,"nodeType":247},{},[],"No attachments were downloaded, thus in this isolated incident there was no code execution on Andrew’s host, meaning that Anti-Virus or Endpoint Detection & Response (EDR) would not have prevented it",{"data":1714,"content":1715,"nodeType":285},{},[1716],{"data":1717,"content":1718,"nodeType":243},{},[1719],{"data":1720,"marks":1721,"value":1722,"nodeType":247},{},[],"The attacker gained full access to Andrew’s mailbox",{"data":1724,"content":1725,"nodeType":243},{},[1726],{"data":1727,"marks":1728,"value":1729,"nodeType":247},{},[],"The malicious app was disabled by Microsoft after some time, so a full investigation into its capabilities was not possible. We don’t know whether another phishing page was presented after the integration took place, thus to be on the safe side we need to assume this happened and led to credential compromise.",{"data":1731,"content":1732,"nodeType":243},{},[1733,1737,1746],{"data":1734,"marks":1735,"value":1736,"nodeType":247},{},[],"The app was unverified, which has historically been true in most of these scenarios. Publishers need to associate a Microsoft Partner Network (MPN) ID with the app, which follows a ",{"data":1738,"content":1740,"nodeType":252},{"uri":1739},"https://docs.microsoft.com/en-us/partner-center/verification-responses",[1741],{"data":1742,"marks":1743,"value":1745,"nodeType":247},{},[1744],{"type":260},"verification process",{"data":1747,"marks":1748,"value":1749,"nodeType":247},{},[],", in order to have it appear as a verified app. This Microsoft 365 tenant was configured to allow unverified integrations due to an oversight following an app migration project.",{"data":1751,"content":1752,"nodeType":243},{},[1753],{"data":1754,"marks":1755,"value":1756,"nodeType":247},{},[],"This leads us to the following to help prevent similar attacks from occurring in future, and to make sure there is no opportunity for the attacker to leverage any existing foothold:",{"data":1758,"content":1759,"nodeType":367},{},[1760,1770,1780,1790,1811,1827,1837],{"data":1761,"content":1762,"nodeType":285},{},[1763],{"data":1764,"content":1765,"nodeType":243},{},[1766],{"data":1767,"marks":1768,"value":1769,"nodeType":247},{},[],"Disable the integration and remove the malicious app’s permissions",{"data":1771,"content":1772,"nodeType":285},{},[1773],{"data":1774,"content":1775,"nodeType":243},{},[1776],{"data":1777,"marks":1778,"value":1779,"nodeType":247},{},[],"Reset Andrew Jenkins’ credentials",{"data":1781,"content":1782,"nodeType":285},{},[1783],{"data":1784,"content":1785,"nodeType":243},{},[1786],{"data":1787,"marks":1788,"value":1789,"nodeType":247},{},[],"Be aware of and review newly created mail rules",{"data":1791,"content":1792,"nodeType":285},{},[1793],{"data":1794,"content":1795,"nodeType":243},{},[1796,1799,1808],{"data":1797,"marks":1798,"value":29,"nodeType":247},{},[],{"data":1800,"content":1802,"nodeType":252},{"uri":1801},"https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/configure-user-consent?tabs=azure-portal",[1803],{"data":1804,"marks":1805,"value":1807,"nodeType":247},{},[1806],{"type":260},"Confirm that the Microsoft 365 tenant is set to disallow integrations from unverified apps",{"data":1809,"marks":1810,"value":29,"nodeType":247},{},[],{"data":1812,"content":1813,"nodeType":285},{},[1814],{"data":1815,"content":1816,"nodeType":367},{},[1817],{"data":1818,"content":1819,"nodeType":285},{},[1820],{"data":1821,"content":1822,"nodeType":243},{},[1823],{"data":1824,"marks":1825,"value":1826,"nodeType":247},{},[],"Note: as of November 9th, 2020, integrations with unverified apps are disabled by default.",{"data":1828,"content":1829,"nodeType":285},{},[1830],{"data":1831,"content":1832,"nodeType":243},{},[1833],{"data":1834,"marks":1835,"value":1836,"nodeType":247},{},[],"Communicate with employees and other affected parties to be weary of these types of attacks",{"data":1838,"content":1839,"nodeType":285},{},[1840],{"data":1841,"content":1842,"nodeType":243},{},[1843],{"data":1844,"marks":1845,"value":1846,"nodeType":247},{},[],"Perform regular audits against your Microsoft 365 tenants to highlight any discrepancies and integrations with unusual or unnecessary permissions.",{"data":1848,"content":1849,"nodeType":243},{},[1850,1854,1863],{"data":1851,"marks":1852,"value":1853,"nodeType":247},{},[],"Microsoft implementing safe defaults towards limiting integrations from unverified publishers was a step in the right direction. However, there have been ",{"data":1855,"content":1857,"nodeType":252},{"uri":1856},"https://www.proofpoint.com/us/blog/cloud-security/oivavoii-active-malicious-hybrid-cloud-threats-campaign",[1858],{"data":1859,"marks":1860,"value":1862,"nodeType":247},{},[1861],{"type":260},"cases",{"data":1864,"marks":1865,"value":1866,"nodeType":247},{},[]," where attackers utilized compromised publishers to perform similar attacks. ",{"data":1868,"content":1869,"nodeType":580},{},[1870],{"data":1871,"marks":1872,"value":1390,"nodeType":247},{},[],{"data":1874,"content":1875,"nodeType":243},{},[1876],{"data":1877,"marks":1878,"value":1879,"nodeType":247},{},[],"While the process isn’t exactly straightforward, catching early indicators like malicious mail rules helps you prevent an attacker from launching additional attacks like phishing campaigns as they try to gain access to sensitive business data. Removing the mail rule is just the start of the process, you really need to revoke permissions and take the other steps we covered in this post to stop an attack from going any further. We’ll publish some more content on SaaS incident response on our blog, so subscribe to get our guidance straight into your inbox.",{"data":1881,"content":1885,"nodeType":526},{"target":1882},{"sys":1883},{"id":1884,"type":346,"linkType":347},"6oHRbGLus4bstsAc7E0zBD",[],{"data":1887,"content":1888,"nodeType":243},{},[1889],{"data":1890,"marks":1891,"value":29,"nodeType":247},{},[],"How to kick off an incident response investigation for a compromised SaaS account","We'll walk through how to quickly detect and mitigate business email compromise (BEC) and then prevent future attacks.","2022-09-20T00:00:00.000Z","how-to-kick-off-an-incident-response-investigation-for-a-compromised-saas",{"items":1897},[1898,1900],{"sys":1899,"name":1078},{"id":1077},{"sys":1901,"name":1903},{"id":1902},"3pjES4THCIfSAwhGdNwBcy","Browser security",{"items":1905},[1906],{"fullName":1907,"firstName":1908,"jobTitle":1909,"profilePicture":1910},"Johann Scheepers","Johann","Senior Security Engineer",{"url":1911},"https://images.ctfassets.net/y1cdw1ablpvd/75IEOH93vR0hbvxuqTu1m3/f6222745ee6892ea07bc18727a5a5ae7/T016S22KZ96-U02LU3SKC2D-e1e755770536-512.png","half-of-account-compromise-attacks-included-malicious-mail-rules","blog/half-of-account-compromise-attacks-included-malicious-mail-rules",{"json":1915},{"data":1916,"content":1917,"nodeType":239},{},[1918],{"data":1919,"content":1920,"nodeType":243},{},[1921],{"data":1922,"marks":1923,"value":1924,"nodeType":247},{},[],"Attackers routinely use mail rules to exfiltrate sensitive data and get persistent access to victim accounts. \n","Attackers routinely use mail rules to hide their attacks, exfiltrate sensitive data, and to get persistent access to victim accounts. \n",{"id":1927,"publishedAt":1928},"4QpaYHe4risfUfjgl13a5q","2025-04-28T18:10:35.840Z",{"items":1930},[1931,1933],{"sys":1932,"name":1074},{"id":1073},{"sys":1934,"name":1078},{"id":1077},"W57EN20QzT1umZHQtFLavgNuAfFhAf1r7ajwojNJXZg",1784196724428]