Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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This rule detects potentially malicious activity against accounts classified as having a high blast radius. It correlates three stages of behavior: observed failed authentication attempts (brute force) against a high-blast-radius account, a password reset for that same account, and a subsequent successful logon outside of standard business hours (using Logon Types 3 or 10). The rule uses a password reset event as the mandatory anchor and flags suspicious sequences of events leading up to or following this change.
Detects a single host rapidly initiating outbound Telnet (port 23) or SSH (port 22) connection attempts against a large number of distinct remote IP addresses in a short window. This behavior is indicative of bot-agent scanners, such as those associated with IoT botnets, attempting to propagate by performing brute-force login attempts using default credential pairs.
Detects high volumes of authentication failures (AADSTS50034) targeting non-existent or invalid usernames from a single source IP address, potentially indicating account enumeration or password spraying activity.
This rule detects potential user enumeration attacks targeting Entra ID tenants by monitoring for failed sign-in attempts (ResultType 50034) involving common, predictable username patterns across multiple tenants within a 24-hour window. This behavior often indicates an adversary attempting to map valid usernames by exploiting error code differences or identity discovery patterns.
Detects potential Resource Owner Password Credential (ROPC) password guessing attempts in Entra ID by monitoring for multiple AADSTS50126 (Invalid Username or Password) errors. Attackers may abuse ROPC to bypass multi-factor authentication requirements or perform brute-force attacks against cloud identities.
Detects Microsoft Entra ID sign-in events where the AppId (OAuth client_id) is a
syntactically valid UUIDv4 but no corresponding AppDisplayName is populated,
indicating the client ID does not correspond to any registered enterprise
application in the tenant. This pattern is consistent with randomly generated,
valid-format spoofed client IDs used in ROPC-based username/password
enumeration.
syntactically valid UUIDv4 but no corresponding AppDisplayName is populated,
indicating the client ID does not correspond to any registered enterprise
application in the tenant. This pattern is consistent with randomly generated,
valid-format spoofed client IDs used in ROPC-based username/password
enumeration.
Detects sign-in activity in Entra ID where the application display name is blank, despite an Application ID being present, originating from known cloud service provider IP ranges (AWS or Cloudflare). This pattern is consistent with automated enumeration or discovery tools that leverage OAuth client ID spoofing or misconfigurations to identify valid tenants or users.
This rule detects potential brute force or password guessing attempts by monitoring Windows security logs for instances where a failed logon (Event ID 4625) is followed by a successful logon (Event ID 4624) for the same user on the same host within a 60-second window.
This rule detects when a user containing the name "admin" in the username fails to log in via SSH.
This could indicate an attempt to access the system using administrative credentials, which may be a sign of malicious activity.
However, it is important to note that this rule may also generate false positives if legitimate users with "admin" in their usernames fail to log in due to typos or other issues.
This could indicate an attempt to access the system using administrative credentials, which may be a sign of malicious activity.
However, it is important to note that this rule may also generate false positives if legitimate users with "admin" in their usernames fail to log in due to typos or other issues.
This rule detects potential brute-force or credential stuffing attempts against web application authentication endpoints by monitoring patterns of success and failure. It aggregates requests over 5-minute intervals, calculating a risk score based on high volumes of authentication failures relative to successful requests from individual source IPs targeting sensitive API paths (e.g., auth, session, login, token).
This rule detects an unusually high number of NTLM logon attempts (more than 3 within a 10-minute window) from a single IP address to various accounts or workstations. This behavior is indicative of a brute-force attack or password guessing attempt against network services, particularly when the logon type is network (3) or remote interactive (10) and not from localhost.
This rule detects potential SSH brute force attacks by monitoring syslog for multiple failed SSH login attempts, connection closures, or invalid user attempts from a single source IP address within a short time frame. It specifically looks for keywords like 'error', 'Connection closed', 'authentication failure', and 'invalid user' in SSHD logs.
This rule detects potential brute force attacks against Microsoft Exchange Outlook Web App (OWA) by monitoring for a high volume of 401 Unauthorized status codes from non-internal IP addresses. It also correlates these authentication events with subsequent post-authentication actions, specifically identifying mailbox logins followed by mailbox searching or export requests, which may indicate account compromise and unauthorized data collection or exfiltration.
Detects high-volume authentication failures originating from a single IP address with a large number of unique target accounts within a 30-minute window, indicative of a password spraying or brute force attack against network services.
This rule detects potential SSH brute force attacks by identifying multiple failed password attempts from a single source IP address to a specific computer within a 5-minute window. It specifically looks for 'Failed password' messages in syslog entries from the 'sshd' process.
Detects multiple failed SSH authentication attempts against a server from a single source within a short timeframe, which is indicative of a brute force password attack.
This rule detects potential brute-force or credential stuffing attempts against web application authentication endpoints by monitoring patterns of success and failure. It aggregates requests over 5-minute intervals, calculating a risk score based on high volumes of authentication failures relative to successful requests from individual source IPs targeting sensitive API paths (e.g., auth, session, login, token).
This rule detects potential brute-force or credential stuffing attempts against web application authentication endpoints by monitoring patterns of success and failure. It aggregates requests over 5-minute intervals, calculating a risk score based on high volumes of authentication failures relative to successful requests from individual source IPs targeting sensitive API paths (e.g., auth, session, login, token).
This rule detects potential brute force or credential stuffing attacks against Azure AD by identifying multiple failed sign-in attempts followed by a successful sign-in from the same user and IP address within a short time frame (1 minute). It specifically looks for scenarios where the successful sign-in occurs after the failed attempts and involves different applications, excluding common Office 365 services to reduce noise.
Detects high-frequency authentication failure events targeting multiple unique user accounts from the same source IP address within a 10-minute window. This behavior is indicative of password spraying or credential stuffing attacks against Azure Active Directory (Microsoft Entra ID). The rule specifically monitors for common error codes related to incorrect passwords or account lockout conditions.
This rule detects potential SSH brute force attacks by identifying high-frequency authentication failures from sshd logs (more than 10 failures in 5 minutes) and rapid, potentially automated connection attempts on port 22 (more than 20 connections in 1 minute) originating from the same source IP on Linux systems.
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