Detections

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

867 detections

The analytic detects the addition of NOPASSWD entries to the /etc/sudoers file on Linux systems. It leverages Linux Auditd data to identify command lines containing "NOPASSWD:". This activity is significant because it allows users to execute commands with elevated privileges without requiring a password, which can be exploited by adversaries to maintain persistent, privileged access. If confirmed malicious, this could lead to unauthorized privilege escalation, persistent access, and potential compromise of sensitive data and system integrity.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
7046
This analytic identifies security events from Microsoft Defender, focusing on Exploit Guard and Attack Surface Reduction (ASR) features. It detects Event IDs 1121, 1126, 1131, and 1133 for blocked operations, and Event IDs 1122, 1125, 1132, and 1134 for audit logs. Event ID 1129 indicates user overrides, while Event ID 5007 signals configuration changes. This detection uses a lookup to correlate ASR rule GUIDs with descriptive names. Monitoring these events is crucial for identifying unauthorized operations, potential security breaches, and policy enforcement issues. If confirmed malicious, attackers could bypass security measures, execute unauthorized actions, or alter system configurations.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0046
The following analytic detects when the risk-based step-up consent security setting in Azure AD is disabled. It monitors Azure Active Directory logs for the "Update authorization policy" operation, specifically changes to the "AllowUserConsentForRiskyApps" setting. This activity is significant because disabling this feature can expose the organization to OAuth phishing threats by allowing users to grant consent to potentially malicious applications. If confirmed malicious, attackers could gain unauthorized access to user data and sensitive information, leading to data breaches and further compromise within the organization.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0045
This analytic identifies when specific Office 365 advanced security settings related to anti-phishing, safe links, safe attachments, or malware protection are altered within the Office 365 tenant. An attacker disabling these settings could reduce their risk of detection, potentially leading to unauthorized data access, data exfiltration, account compromise, or other malicious activities without leaving a detailed audit trail.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1045
The analytic detects modifications to default Group Policy Objects (GPOs) using Event ID 5136. It monitors changes to the `Default Domain Controllers Policy` and `Default Domain Policy`, which are critical for enforcing security settings across domain controllers and all users/computers, respectively. This activity is significant because unauthorized changes to these GPOs can indicate an adversary with privileged access attempting to deploy persistence mechanisms or execute malware across the network. If confirmed malicious, such modifications could lead to widespread compromise, allowing attackers to maintain control and execute arbitrary code on numerous hosts.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1044
This detection identifies an Active Directory access-control list (ACL) modification event, which applies the minimum required extended rights to perform the DCShadow attack. Specifically, it looks for modifications to the domainDNS object where specific GUIDs related to 'Add/Remove Replica In Domain', 'Manage Replication Topology', and 'Replication Synchronization' are added to the ACL. These permissions are necessary for an attacker to register a rogue domain controller and perform a DCShadow attack.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1042
The following analytic identifies when a policy is deleted in AWS. It leverages Amazon Security Lake logs to detect the DeletePolicy API operation. Monitoring policy deletions is crucial as it can indicate unauthorized attempts to weaken security controls. If confirmed malicious, this activity could allow an attacker to remove critical security policies, potentially leading to privilege escalation or unauthorized access to sensitive resources.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
3041
The analytic detects modifications in the Windows registry by the Applocker utility that deny the execution of various security products. This detection leverages data from the Endpoint.Registry datamodel, focusing on specific registry paths and values indicating a "Deny" action against known antivirus and security software. This activity is significant as it may indicate an attempt to disable security defenses, a tactic observed in malware like Azorult. If confirmed malicious, this could allow attackers to bypass security measures, facilitating further malicious activities and persistence within the environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0041
The analytic detects the disablement of security steps in a CircleCI pipeline. This activity is significant because disabling security steps can introduce vulnerabilities, unauthorized changes, or malicious code into the pipeline. If confirmed malicious, this could lead to potential attacks, data breaches, or compromised infrastructure. The rule leverages CircleCI logs, using field renaming, joining, and statistical analysis to identify instances where mandatory security steps are not executed. Investigation should focus on reviewing job names, commit details, and user information associated with the disablement, and examining any relevant artifacts and concurrent processes.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0040
This rule detects modifications to the Access Control List (ACL) of the domain root object in Active Directory. Such modifications are significant and can have a high impact on the security of the Active Directory environment. The rule specifically looks for EventCode 5136 (A directory service object was modified) where the ObjectClass is 'domainDNS'. It then parses the old and new ACL values to identify specific changes, including the type of access control entry (ACE), flags, access rights, and the security identifier (SID) of the user or group affected. The rule also attempts to resolve SIDs to user or group names for better readability. Microsoft guidance suggests that all changes at this level should be reviewed.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0040
This analytic is looking for when an ACL is applied to an OU which denies listing the objects residing in the OU. This activity combined with modifying the owner of the OU will hide AD objects even from domain administrators.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1040
The analytic identifies attempts to bypass AppLocker application restrictions by monitoring specific Windows AppLocker event codes (8007, 8004, 8022, 8025, 8029, 8040). These event codes indicate block events where an application was prevented from running due to AppLocker policies. The rule focuses on instances where five or more such attempts occur from the same source, which could suggest an attacker trying to escalate privileges or execute unauthorized code on the system. It extracts details such as the host, full file path, and target user associated with the bypass attempt.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1040
The following analytic identifies when a Windows Defender ASR rule disabled events. ASR is a feature of Windows Defender Exploit Guard that prevents actions and apps that are typically used by exploit-seeking malware to infect machines. ASR rules are applied to processes and applications. When a process or application attempts to perform an action that is blocked by an ASR rule, an event is generated. This detection searches for ASR rule disabled events that are generated when an ASR rule is disabled.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0040
The following analytic detects the use of PowerShell commands to add or set Windows Defender exclusions. It leverages EventCode 4104 to identify suspicious `Add-MpPreference` or `Set-MpPreference` commands with exclusion parameters. This activity is significant because adversaries often use it to bypass Windows Defender, allowing malicious code to execute without detection. If confirmed malicious, this behavior could enable attackers to evade antivirus defenses, maintain persistence, and execute further malicious activities undetected.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0039
This detection identifies instances where a Windows Firewall rule has been deleted, potentially exposing the system to security risks. Unauthorized removal of firewall rules can indicate an attacker attempting to bypass security controls or malware disabling protections for persistence and command-and-control communication. The event logs details such as the deleted rule name, protocol, port, and the user responsible for the action. Security teams should monitor for unexpected deletions, correlate with related events, and investigate anomalies to prevent unauthorized access and maintain network security posture.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1039
The following analytic identifies the creation of a new AWS IAM policy version that allows access to all resources. It detects this activity by analyzing AWS CloudTrail logs for the CreatePolicyVersion event with a policy document that grants broad permissions. This behavior is significant because it violates the principle of least privilege, potentially exposing the environment to misuse or abuse. If confirmed malicious, an attacker could gain extensive access to AWS resources, leading to unauthorized actions, data exfiltration, or further compromise of the AWS environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0038
The following analytic detects when two-factor authentication (2FA) requirements are disabled in GitHub Enterprise. The detection monitors GitHub Enterprise audit logs for 2FA requirement changes by tracking actor details, organization information, and associated metadata. For a SOC, identifying disabled 2FA requirements is critical as it could indicate attempts to weaken account security controls. Two-factor authentication is a fundamental security control that helps prevent unauthorized access even if passwords are compromised. Disabling 2FA requirements could allow attackers to more easily compromise accounts through password-based attacks. The impact of disabled 2FA includes increased risk of account takeover, potential access to sensitive code and intellectual property, and compromise of the software supply chain. This activity could be part of a larger attack chain where an adversary first disables security controls before attempting broader account compromises.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1038
This detection identifies instances where a Windows Firewall rule has been modified, which may indicate an attempt to alter security policies. Unauthorized modifications can weaken firewall protections, allowing malicious traffic or preventing legitimate communications. The event logs details such as the modified rule name, protocol, ports, application path, and the user responsible for the change. Security teams should monitor unexpected modifications, correlate them with related events, and investigate anomalies to prevent unauthorized access and maintain network security integrity.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1038
The analytic detects the enabling of the SMB1 protocol via `powershell.exe`. It leverages PowerShell script block logging (EventCode 4104) to identify the execution of the `Enable-WindowsOptionalFeature` cmdlet with the `SMB1Protocol` parameter. This activity is significant because enabling SMB1 can facilitate lateral movement and file encryption by ransomware, such as RedDot. If confirmed malicious, this action could allow an attacker to propagate through the network, encrypt files, and potentially disrupt business operations.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1037
This detection identifies when an Active Directory Group Policy is deleted using the Group Policy Management Console. Deleting Group Policy Objects (GPOs) can be a legitimate administrative action, but it can also be used by adversaries to remove security controls, disable logging, or clean up traces of their activity. Monitoring for GPO deletions is crucial for maintaining the integrity of an Active Directory environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0036
This rule detects when the owner of an Active Directory object is updated. Changing an object's owner grants full control over that object, which can be a significant privilege escalation or a precursor to hiding an AD object. The rule specifically looks for EventCode 5136 in Windows Security Event Logs, filtering for changes in the 'owner' attribute.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0036
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