Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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Detects a high volume of outbound emails (more than 20 within a one-hour window) from a single sender containing the subject line 'Payment Transaction Failed Reminder', which is a common pattern for phishing or social engineering campaigns.
Detects anomalous reuse of an authenticated Microsoft 365 session cookie shortly after a successful MFA-satisfied sign-in. The detection identifies scenarios where the subsequent access originates from a different IP address, device, or user agent without an intervening MFA challenge, which is a pattern indicative of session hijacking techniques like Adversary-in-the-Middle (AiTM) or session token replay.
This rule detects potential phishing activity by correlating email delivery events and URL click events against a set of known malicious domains and suspicious URL paths. It identifies when a user receives an email containing a suspicious link or interacts with such a link, providing visibility into potential credential harvesting or malware delivery attempts.
This rule detects potential phishing activity by correlating email delivery events and URL click events against a set of known malicious domains and suspicious URL paths. It identifies when a user receives an email containing a suspicious link or interacts with such a link, providing visibility into potential credential harvesting or malware delivery attempts.
This rule identifies potentially compromised Entra ID accounts by correlating multiple suspicious behaviors within a 14-day window. It aggregates four specific indicators: successful authentication following repeated MFA failures, impossible travel (sign-ins from multiple countries within a short timeframe), unusual hour logons (00:00-05:00), and sign-ins flagged with medium/high risk or reported as compromised. The rule triggers when an account exhibits two or more of these distinct anomalous behaviors.
This rule monitors for email events where the email is flagged for suspicious properties (SPF/DKIM/DMARC failure, threat categorization) and includes potentially malicious attachments or URLs. It then correlates these suspicious emails with subsequent process execution events on the recipient's endpoint within a 30-minute window, identifying a potential successful execution of a phishing payload.
Detects successful authentication to Microsoft Teams or Slack where MFA was successfully completed, but the device is reported as unmanaged or non-compliant and is accompanied by sign-in risk signals. This behavior is consistent with Adversary-in-the-Middle (AitM) proxy attacks where an attacker captures credentials and session tokens, bypassing MFA, and using the hijacked session from an unrecognized device or location.
This rule identifies potential phishing emails that impersonate OneDrive sharing notifications. It correlates email messages containing keywords typically associated with document sharing (e.g., 'OneDrive', 'shared', 'file') with subsequent user URL clicks. Crucially, the rule filters for clicks to domains that are not explicitly related to legitimate OneDrive, SharePoint, or 1drv.ms hosting, indicating a potential attempt to lure users to a malicious third-party site under the guise of file sharing.
Detects incoming emails that impersonate DocuSign notifications, specifically looking for typical phishing lures involving 'Remittance Advice' and a call-to-action to 'Tap here to view document'. This rule identifies emails using common social engineering tactics to harvest credentials or distribute malware via fake document links.
Detects high-volume internal email campaigns that exhibit characteristics of phishing, specifically utilizing sender display name impersonation of executive or IT support roles, urgent subject lines, and URLs identified as malicious by threat intelligence. The rule tracks common attributes like SPF/DKIM/DMARC failures and rapid delivery to multiple recipients.
Detects anomalous sign-in behavior shortly after a successful MFA-authenticated session in Microsoft 365. This rule flags scenarios where a subsequent session for the same user occurs within a short window (30 minutes) from a different IP, ASN, User-Agent, or device identifier, potentially indicating the replay of a stolen session cookie obtained via Adversary-in-the-Middle (AiTM) phishing.
Detects incoming emails from an external domain where the email subject contains the recipient's normalized local name. This is a common pattern for targeted phishing or 'CEO fraud' style attacks where the subject is crafted to mimic personalized or internal communications.
Microsoft Graph API Calendar C2 Activity
Cortex XDR
Detects anomalous Microsoft Graph API activity targeting calendar events and attachments, indicative of the HOLLOWGRAPH C2 protocol. The rule identifies application identity accounts using non-browser user agents to perform suspicious operations (e.g., creating events with future-dated timestamps, specific subject tag formats like 'Boss{..}ID{..}' or 'Event ID:', and file attachments named 'File{n}.txt'). This pattern suggests the use of a compromised M365 mailbox as a two-way dead-drop for C2 and data exfiltration.
This rule identifies phishing attempts by detecting inbound emails where the sender's domain or any embedded URLs within the email content match a pre-defined list of known malicious domains. It flags emails for further investigation by correlating sender domain data and URL information found in the email communication.
Detects a high volume of outbound emails (more than 20 within a one-hour window) from a single sender containing the subject line 'Payment Transaction Failed Reminder', which is a common pattern for phishing or social engineering campaigns.
This rule detects high-frequency account and email address enumeration attempts. It monitors syslog data for SMTP commands such as VRFY, EXPN, or RCPT TO, and analyzes Microsoft Entra ID (SigninLogs) for authentication failures specifically associated with error code 50034 (user not found). Both behaviors are indicative of an adversary attempting to validate user identities within an environment, often as a precursor to targeted phishing or brute-force attacks.
This rule identifies suspicious emails containing password-protected attachments or files often used to bypass email security gateways. It monitors for emails where the subject line includes password hints or keywords like 'protected' or 'secure', combined with the presence of attachments and URL-based links, which are common tactics in phishing campaigns to distribute malicious payloads.
This rule detects OAuth authorization requests (targeting Microsoft or Google identity providers) that use 'prompt=none' (silent authentication) and redirect the user to an unexpected or untrusted domain. This pattern is commonly used in OAuth consent phishing or token theft attacks, where an attacker attempts to silently acquire an authorization code by redirecting it to a malicious application server instead of the legitimate service provider's domain.
Detects signs of Adversary-in-the-Middle (AiTM) phishing kits by identifying sequential, rapid-fire attempts to authenticate using multiple distinct MFA methods (such as push notifications, TOTP codes, or SMS) within a single sign-in session. These attempts are combined with explicit failure states (rejected passwords, rejected codes, or denied MFA requests), suggesting an attacker is relaying authentication challenges in real-time to a victim.
Detects Direct Send spearphishing impersonating internal roles (IT/Finance/Procurement) with business-themed lures targeting leadership/finance titles. Rewritten: removed a non-functional sender/recipient substring check and a broken EmailPostDeliveryEvents join that made the rule rarely fire; anchored detection to the actual Direct Send signature (null envelope + domain match) and a direct IdentityInfo join; standardized auth-failure parsing to match the other rules in this set.
Detects inbound emails where the sender domain mimics finance-themed brands (using a regex-based pattern) and includes URLs redirecting through the ActiveCampaign platform tracking domains (activehosted.com or acemlnd.com). This rule identifies potential phishing campaigns attempting to use legitimate email marketing infrastructure to bypass reputation-based filters.
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