Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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M365 Malicious Mailbox Rule Abuse
Cortex XDR
Detects the creation or modification of Microsoft 365 Exchange inbox rules that exhibit characteristics of malicious behavior, such as using trivial or blank names, moving items to rarely-monitored folders (e.g., 'Conversation History', 'RSS Feeds'), or containing keywords related to phishing, credential harvesting, or financial fraud.
Detects mail redirection on Zimbra Collaboration. Zimbra is widely deployed in
government, education and smaller enterprises, has been the subject of repeated
mass-exploitation campaigns, and is rarely covered by commercial detection content —
the combination makes it a persistent soft target.
Redirection is the standard persistence on a compromised mailbox: it survives
password resets and quietly copies correspondence onward.
Onboarding: ZIMBRA is ingested via Syslog (Bloo extractor 123).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='ZIMBRA' and action='EMAIL_REDIRECTED'
| groupby sender, recipient, direction, remoteip, subject
government, education and smaller enterprises, has been the subject of repeated
mass-exploitation campaigns, and is rarely covered by commercial detection content —
the combination makes it a persistent soft target.
Redirection is the standard persistence on a compromised mailbox: it survives
password resets and quietly copies correspondence onward.
Onboarding: ZIMBRA is ingested via Syslog (Bloo extractor 123).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='ZIMBRA' and action='EMAIL_REDIRECTED'
| groupby sender, recipient, direction, remoteip, subject
Detects a message having its recipient altered during processing. Recipient
rewriting redirects mail away from its intended reader, and is a quiet way to
intercept correspondence or to suppress a notification that would otherwise reveal
an ongoing compromise.
Onboarding: TREND-MICRO-DDEI is ingested via Syslog (CEF) (Bloo extractor 265).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='TREND-MICRO-DDEI'
and action='EMAIL_RECIPIENT_CHANGED'
| groupby sender, recipient, direction, remoteip
rewriting redirects mail away from its intended reader, and is a quiet way to
intercept correspondence or to suppress a notification that would otherwise reveal
an ongoing compromise.
Onboarding: TREND-MICRO-DDEI is ingested via Syslog (CEF) (Bloo extractor 265).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='TREND-MICRO-DDEI'
and action='EMAIL_RECIPIENT_CHANGED'
| groupby sender, recipient, direction, remoteip
Detects mail being redirected to an external recipient. Redirection rules are the
classic persistence mechanism on a compromised mailbox: they survive password resets,
require no further access, and quietly copy correspondence to the attacker for as
long as they remain in place.
This is among the most under-monitored controls in most estates, because the rule is
set once and never fires an alert again.
Onboarding: MS-EXCHANGE is ingested via Syslog (Bloo extractor 142).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='MS-EXCHANGE'
and action='EMAIL_REDIRECTED'
| groupby sender, recipient, direction, remoteip
classic persistence mechanism on a compromised mailbox: they survive password resets,
require no further access, and quietly copy correspondence to the attacker for as
long as they remain in place.
This is among the most under-monitored controls in most estates, because the rule is
set once and never fires an alert again.
Onboarding: MS-EXCHANGE is ingested via Syslog (Bloo extractor 142).
Integration guide: https://bloo.io/docs/hypercloud/syslog-connector
BQL (Bloo Query Language):
stream=email-gateway where sourcename='MS-EXCHANGE'
and action='EMAIL_REDIRECTED'
| groupby sender, recipient, direction, remoteip
Detects the creation or modification of Exchange mailbox rules using the New-InboxRule or Set-InboxRule cmdlets that perform automatic forwarding or redirection of email to external, non-trusted domains. This technique is commonly employed during account takeover events to facilitate covert data exfiltration.
Detects the creation or modification of inbox rules in Microsoft 365 Exchange environments that perform suspicious actions such as forwarding, redirecting, moving, or deleting emails. This rule specifically monitors for rule configurations that target potentially sensitive keywords, indicating a likely attempt to exfiltrate data, hide security alerts, or intercept communications.
Detects the creation or modification of Exchange Online inbox rules that configure automatic email forwarding or redirection to an external domain. The rule specifically flags if the action also involves deleting or hiding the message, which is a common persistence and exfiltration technique used in Business Email Compromise (BEC) attacks. The detection also incorporates correlation with recent high-risk sign-in activity for the associated user account.
Detects the creation or modification of Microsoft 365/Exchange inbox rules that suggest malicious staging or exfiltration activities. This includes rules configured for external email auto-forwarding, automatic deletion of messages, or movement of emails into hidden/system folders (e.g., RSS Subscriptions, Archive) which may be filtered based on sensitive keywords related to financial or credential theft (e.g., invoice, wire, payment).
Detects the creation or modification of mailbox inbox rules that configure forwarding or redirection to external addresses, or rules that automatically delete or move messages based on sensitive keyword filters (e.g., 'invoice', 'password'). It specifically looks for indicators of mailbox hiding (hidden rules) which are frequently used by attackers to maintain persistence and conceal activity, particularly following unauthorized access or token theft.
Detects potential account compromise by aggregating multiple high-fidelity indicators of adversary activity for a single user within a 72-hour window. The rule triggers when at least three distinct stages of an attack chain are identified, specifically: credential theft/infostealer activity, anomalous sign-in (token reuse/impossible travel), mailbox or OAuth configuration changes, and mass data exfiltration.
This rule detects potentially malicious inbox rule creation or modification in Office 365 Exchange. It flags rules that contain keywords associated with financial fraud (e.g., invoice, wire, payment) and include actions that hide evidence (e.g., moving messages to junk or deleting them). It further correlates these actions with suspicious user login activity, such as logging in from a new IP address or country within an hour of the rule change, which is a common indicator of a Business Email Compromise (BEC) account takeover.
This rule detects a multi-stage Business Email Compromise (BEC) attack involving executive impersonation via look-alike domains, followed by the creation of suspicious inbox rules (forwarding/deletion) by the victim, and concurrent external communication (Teams/Zoom meeting invites) from a newly created account. It correlates these activities to identify sophisticated payment fraud campaigns.
Detects the creation of suspicious O365 inbox rules designed to hide (via mark-as-read, move, or delete actions) or forward/redirect email messages containing keywords associated with financial transactions such as payment, wire, or invoice. This behavior is indicative of post-compromise activity, specifically targeted at invoice fraud or email thread hijacking.
Detects a potential Business Email Compromise (BEC) persistence chain where a user grants an OAuth application mail-read or mail-write permissions, followed by the creation of a malicious inbox rule designed to forward, move, or delete sensitive email threads. This combination enables persistent exfiltration and stealth, bypassing password resets as the OAuth token remains active.
Detects a potential Business Email Compromise (BEC) persistence chain where a user grants an OAuth application mailbox read/write permissions, followed immediately by the creation of an inbox rule (forwarding, moving, or deleting) targeting messages containing keywords like 'invoice', 'wire', or 'payment'.
Detects a potential Business Email Compromise (BEC) persistence chain where a user grants an OAuth application mailbox read/write permissions, followed immediately by the creation of an inbox rule (forwarding, moving, or deleting) targeting messages containing keywords like 'invoice', 'wire', or 'payment'.
Detects a potential Business Email Compromise (BEC) persistence chain where a user grants an OAuth application mailbox read/write permissions, followed immediately by the creation of an inbox rule (forwarding, moving, or deleting) targeting messages containing keywords like 'invoice', 'wire', or 'payment'.
Detects the creation or modification of Microsoft 365/Exchange inbox rules that suggest malicious staging or exfiltration activities. This includes rules configured for external email auto-forwarding, automatic deletion of messages, or movement of emails into hidden/system folders (e.g., RSS Subscriptions, Archive) which may be filtered based on sensitive keywords related to financial or credential theft (e.g., invoice, wire, payment).
Detects the creation or modification of Exchange inbox rules that involve suspicious actions, such as forwarding or redirecting emails to external domains, deleting messages, or marking messages as read. These actions are common indicators of persistent access or data exfiltration attempts following a mailbox compromise.
Detects mailbox configuration changes in Exchange Online where email forwarding (ForwardingSmtpAddress, ForwardingAddress, or DeliverToMailboxAndForward) is enabled to an external, non-tenant domain. This technique is commonly used for persistence and data exfiltration following account compromise, allowing attackers to redirect incoming communications to an external mailbox even after the original account credentials have been reset.
This rule detects a multi-stage Business Email Compromise (BEC) attack involving executive impersonation via look-alike domains, followed by the creation of suspicious inbox rules (forwarding/deletion) by the victim, and concurrent external communication (Teams/Zoom meeting invites) from a newly created account. It correlates these activities to identify sophisticated payment fraud campaigns.
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