Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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This analytic detects the use of known suspicious SSL certificates by comparing the SHA1 fingerprint from Cisco Secure Firewall logs against a blacklist. This is crucial for identifying malware distribution, C2 infrastructure, or phishing campaigns that reuse or self-sign certificates. Detection of such activity may indicate beaconing, malware download, or data exfiltration over TLS/SSL.
This analytic detects when a new certificate is requested or granted against Active Directory Certificate Services (AD CS) using a Subject Alternative Name (SAN). It leverages Windows Security Event Codes 4886 (A certificate was issued or denied) and 4887 (A certificate request was approved and a certificate was issued) to identify these actions. This activity is significant because improperly configured certificate templates can be exploited for privilege escalation and environment compromise. If confirmed malicious, an attacker could gain elevated privileges or persist within the environment, potentially leading to unauthorized access to sensitive information and further exploitation.
The analytic detects when a new certificate is requested from Active Directory Certificate Services (AD CS) by monitoring Windows Event ID 4886. Unauthorized certificate requests can be a tactic for credential theft or lateral movement. If malicious, an attacker could use the certificate to impersonate users, gain unauthorized access, or establish persistence. Monitoring this event, especially in correlation with other suspicious activities, is crucial for identifying potential security incidents.
The following analytic detects the export of a certificate from the Windows Certificate Store. It leverages the Certificates Lifecycle log channel, specifically event ID 1007, to identify this activity. Monitoring certificate exports is crucial as certificates can be used for authentication to VPNs or private resources. If malicious actors export certificates, they could potentially gain unauthorized access to sensitive systems or data, leading to significant security breaches.
The analytic identifies the backup of the Active Directory Certificate Services (AD CS) store, detected via Event ID 4876. This event is logged when a backup is performed using the CertSrv.msc UI or the CertUtil.exe -BackupDB command. Monitoring this activity is crucial as unauthorized backups can indicate an attempt to steal authentication certificates, which are critical for secure communications. If confirmed malicious, this activity could allow an attacker to impersonate users, escalate privileges, or access sensitive information, severely compromising the security of the environment.
This analytic detects SSL certificates with Punycode domains in the SSL issuer email domain, identified by the prefix "xn--". It leverages the Certificates Datamodel to flag these domains and uses CyberChef for decoding. This activity is significant as Punycode can be used for domain spoofing and phishing attacks. If confirmed malicious, attackers could deceive users and systems, potentially leading to unauthorized access and data breaches.
This analytic identifies the use of `certutil.exe` with arguments indicating the manipulation or extraction of certificates. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line arguments. This activity is significant because extracting certificates can allow attackers to sign new authentication tokens, particularly in federated environments like Windows ADFS. If confirmed malicious, this could enable attackers to forge authentication tokens, potentially leading to unauthorized access and privilege escalation within the network.
The following analytic detects the installation of a root CA certificate by monitoring specific registry paths for SetValue events. It leverages data from the Endpoint datamodel, focusing on registry paths containing "certificates" and registry values named "Blob." This activity is significant because unauthorized root CA certificates can compromise the integrity of encrypted communications and facilitate man-in-the-middle attacks. If confirmed malicious, this could allow an attacker to intercept, decrypt, or manipulate sensitive data, leading to severe security breaches.
This analytic identifies the issuance of a new certificate by Certificate Services - AD CS, detected via Windows Event ID 4887. This event logs the requester user context, DNS hostname of the requesting machine, and the request time. Monitoring this activity is crucial as it can indicate potential misuse of authentication certificates. If confirmed malicious, an attacker could use the issued certificate to impersonate users, escalate privileges, or maintain persistence within the environment. This detection helps in identifying and correlating suspicious certificate-related activities for further investigation.
The following analytic detects the presence of punycode within x509 certificates using Zeek x509 logs. It identifies punycode in the subject alternative name email and other fields by searching for the "xn--" prefix. This activity is significant as punycode can be used in phishing attacks or to bypass domain filters, posing a security risk. If confirmed malicious, attackers could use these certificates to impersonate legitimate domains, potentially leading to unauthorized access or data breaches.
The following analytic identifies potential threats related to the theft or forgery of authentication certificates. It detects when five or more analytics from the Windows Certificate Services story trigger within a specified timeframe. This detection leverages aggregated risk scores and event counts from the Risk data model. This activity is significant as it may indicate an ongoing attack aimed at compromising authentication mechanisms. If confirmed malicious, attackers could gain unauthorized access to sensitive systems and data, potentially leading to severe security breaches.
The analytic detects `CertUtil.exe` performing a backup of the Certificate Store. This activity is significant because it may indicate an attempt to steal authentication certificates, which are critical for secure communications. If confirmed malicious, an attacker could use the stolen certificates to impersonate users, decrypt sensitive data, or gain unauthorized access to systems, leading to severe security breaches.
The following analytic detects the use of the PowerShell cmdlet 'export-certificate' executed via the command line, indicating an attempt to export a certificate from the local Windows Certificate Store. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs and command-line arguments. Exporting certificates is significant as it may indicate credential theft or preparation for man-in-the-middle attacks. If confirmed malicious, this activity could allow an attacker to impersonate users, decrypt sensitive communications, or gain unauthorized access to systems and data.
The analytic detects the use of the PowerShell cmdlet `Export-PfxCertificate` on the command line, indicating an attempt to export a certificate from the local Windows Certificate Store. This activity is significant as it may indicate an attempt to exfiltrate authentication certificates, which can be used to impersonate users or decrypt sensitive data. If confirmed malicious, this could lead to unauthorized access and potential data breaches.
Detects the creation or update of Active Directory Certificate Services (AD CS) certificate templates that are configured with risky Extended Key Usages (EKUs) and allow the enrollee to supply the subject. This combination can be exploited for privilege escalation and credential access, as described in the 'Certified Pre-Owned' whitepaper, by allowing an attacker to request certificates with arbitrary subject names, potentially impersonating privileged accounts.
This rule detects the creation or update of Active Directory Certificate Services (AD CS) certificate templates that include the 'CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT' flag. This flag allows a user to specify the subject name in a certificate request, which can be abused for privilege escalation or credential access, particularly in scenarios involving misconfigured AD CS environments as described in the 'Certified Pre-Owned' research.
Detects the installation of new root certificates on a Linux system. Attackers may install root certificates to bypass security warnings when connecting to adversary-controlled web servers or C2 infrastructure, making their malicious traffic appear legitimate. This rule specifically looks for the execution of common Linux utilities used for managing CA certificates: 'update-ca-certificates' and 'update-ca-trust'.
Detects when an application exports a certificate (and potentially the private key as well) from the local Windows certificate store. This activity can be indicative of an adversary attempting to steal authentication certificates for various malicious purposes, including lateral movement, persistence, or privilege escalation.
This rule detects when an application acquires a certificate private key. This event (EventID 70 in the CAPI2 Operational log) indicates that a private key associated with a certificate has been accessed or exported. This activity can be indicative of an adversary attempting to steal or gain access to authentication certificates for various malicious purposes, such as impersonation or persistence.
This rule detects the installation of a root certificate on a Windows system via PowerShell. It specifically looks for PowerShell script block text containing commands like 'Move-Item' or 'Import-Certificate' targeting the 'Cert:\LocalMachine\Root' path. Adversaries may install root certificates to bypass security warnings when connecting to their controlled web servers, facilitating man-in-the-middle attacks or credential harvesting.
Detects PowerShell script blocks that contain commands used to export certificates from the local certificate store. This activity can be abused by threat actors to steal private keys from compromised machines.
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