Detections

Explore public detection logic contributed by the community across SIEM and rule languages.

782 detections

Detects credential stuffing in Entra ID sign-in logs: one source IP failing against many distinct accounts within an hour, then succeeding on a small number of them.
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Arnold Chan@slaz
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Midnight Slayer
22 days ago
004
The following analytic identifies a single source endpoint failing to authenticate with 30 unique valid users using the NTLM protocol. It leverages EventCode 4776 from Domain Controller logs, focusing on error code 0xC000006A, which indicates a bad password. This behavior is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges. If confirmed malicious, this activity could lead to unauthorized access to sensitive information or further compromise of the Active Directory environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
18 days ago
001
Detects sign-in activity originating from a known suspicious VPN/proxy IP range targeting critical Microsoft 365 applications. The rule specifically monitors for instances where multi-factor authentication (MFA) enforcement appears to be absent or failed, suggesting a potential account compromise and subsequent data access attempt via a proxy/VPN.
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Ankit Mehta@Secvyn
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SlimKQL 2026
1 month ago
24020
Detects credential stuffing in Entra ID sign-in logs: one source IP failing against many distinct accounts within an hour, then succeeding on a small number of them.
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Arnold Chan@slaz
Defender - KQL
22 days ago
002
Detects Microsoft Entra ID (formerly Azure AD) sign-in attempts that use the specific, hardcoded User-Agent string associated with the TeamFiltration tool. This tool is frequently used for mass credential testing against Microsoft 365 environments. The detection looks for a suspicious and outdated combination of Teams, Electron, and Chrome versions that would not be present in legitimate, modern Microsoft Teams client traffic.
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Ankit Mehta@Secvyn
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SlimKQL 2026
1 month ago
6017
Detects credential stuffing in Entra ID sign-in logs: one source IP failing against many distinct accounts within an hour, then succeeding on a small number of them.
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Arnold Chan@slaz
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Hunters
22 days ago
201
Detects credential stuffing in Entra ID sign-in logs: one source IP failing against many distinct accounts within an hour, then succeeding on a small number of them.
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Arnold Chan@slaz
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Detection & Hunting Community
22 days ago
001
Detects the initiation of VPN or ICA sessions on Citrix NetScaler devices where there is no record of a corresponding successful AAA (Authentication, Authorization, and Accounting) login event from the same source IP address within a one-hour lookback window. This pattern may indicate potential authentication bypass attempts, such as those associated with recent vulnerabilities in NetScaler products.
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Ibrahim Saud@tektrix
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Detections.ai Community
1 month ago
7021
This rule detects potential password spraying activity by monitoring for a single source IP address that targets multiple distinct user accounts with failed authentication attempts. It specifically identifies 'low-and-slow' patterns that may attempt to evade standard lockout thresholds, and flags cases where legacy authentication protocols are utilized, a technique commonly employed to bypass Multi-Factor Authentication (MFA).
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Ankit Mehta@Secvyn
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Detections.ai Community
1 month ago
15019
This rule monitors Linux system authentication logs to identify potential unauthorized access attempts. It triggers when a single source IP initiates a high volume of failed SSH login attempts (brute force) or when a single user account is targeted by multiple distinct source IPs within a short time window (password spraying).
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Ankit Mehta@Secvyn
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Detections.ai Community
30 days ago
607
Detects a sequence of authentication activity indicative of a credential stuffing attack. The rule identifies a burst of failed password-only authentication attempts followed by a successful authentication for the same account. It requires that the IP address used for the successful login overlaps with the set of IPs that initiated the failed attempts, effectively filtering out typical user noise and highlighting potentially malicious activity where an attacker has identified a valid credential.
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Arnold Chan@slaz
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Detection & Hunting Community
1 month ago
107
Detects anomalous authentication patterns where a single source IP targets a high number of unique user accounts with failed authentication attempts over a rolling window. By filtering out SSO/Federated methods and specific service account patterns, this rule isolates low-and-slow brute-force or password-spraying activities designed to evade standard account lockout mechanisms.
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Ankit Mehta@Secvyn
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Detections.ai Community
30 days ago
006
Detects anomalous AWS activity combining bulk secret retrieval from AWS Secrets Manager using the BatchGetSecretValue API with subsequent authentication failures or validation errors in AWS STS. This behavior is indicative of automated credential harvesting pipelines or agentic frameworks rapidly enumerating and testing stolen credentials.
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Ibrahim Saud@tektrix
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Detections.ai Community
1 month ago
0032
This rule detects a password-spraying attack pattern directed at privileged or manager-titled accounts. It monitors for multiple failed sign-in attempts from a single source IP address against a large volume of distinct user accounts identified as managers or senior staff. The detection logic filters for low-frequency attempts per account, which is indicative of a distributed spray attack designed to evade account lockout thresholds while focusing on high-value targets.
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Arnold Chan@slaz
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Detection & Hunting Community
1 month ago
1013
Detects a sequence of authentication activity indicative of a credential stuffing attack. The rule identifies a burst of failed password-only authentication attempts followed by a successful authentication for the same account. It requires that the IP address used for the successful login overlaps with the set of IPs that initiated the failed attempts, effectively filtering out typical user noise and highlighting potentially malicious activity where an attacker has identified a valid credential.
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Arnold Chan@slaz
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Hunters
1 month ago
105
Detects a sequence of authentication activity indicative of a credential stuffing attack. The rule identifies a burst of failed password-only authentication attempts followed by a successful authentication for the same account. It requires that the IP address used for the successful login overlaps with the set of IPs that initiated the failed attempts, effectively filtering out typical user noise and highlighting potentially malicious activity where an attacker has identified a valid credential.
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Arnold Chan@slaz
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Detections.ai Community
1 month ago
005
This rule identifies potential brute force or password spraying attacks against network edge devices, such as firewalls and VPN gateways. It aggregates authentication failures and denied connection attempts by source IP address. The rule differentiates between brute force attacks, characterized by a high volume of failed attempts against one or more users from a single source, and password spraying, indicated by multiple unique usernames failing authentication from the same source.
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Ankit Mehta@Secvyn
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Detections.ai Community
30 days ago
004
This rule detects potential brute-force activity against remote access services (OpenVPN, StrongSwan, WireGuard, and SSH) on Linux hosts by monitoring Syslog for patterns indicating repeated failed authentication attempts. It further highlights instances where a burst of failed attempts is followed by a successful authentication for the same source IP, indicating a potential successful compromise.
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Ankit Mehta@Secvyn
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Detections.ai Community
30 days ago
204
Detects repeated SSH authentication failures originating from an external source on port 22, where the username pattern appears to be programmatically generated or enumerated (e.g., username followed by digits). This behavior is characteristic of automated brute-force attempts targeting common SSH services.
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Ankit Mehta@Secvyn
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Detections.ai Community
30 days ago
004
Detects a sequence of authentication activity indicative of a credential stuffing attack. The rule identifies a burst of failed password-only authentication attempts followed by a successful authentication for the same account. It requires that the IP address used for the successful login overlaps with the set of IPs that initiated the failed attempts, effectively filtering out typical user noise and highlighting potentially malicious activity where an attacker has identified a valid credential.
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Arnold Chan@slaz
Defender - KQL
1 month ago
004
This rule detects a credential-based attack where a single source IP performs multiple failed RDP (LogonType 3/10) attempts against various user accounts, followed by a successful authentication from the same source within an hour. This pattern is indicative of password spraying or brute-forcing followed by successful lateral movement via Remote Desktop.
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Ibrahim Saud@tektrix
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Detections.ai Community
1 month ago
404
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