{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/memssp/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["Elastic Defend","Microsoft Defender XDR","SentinelOne Cloud Funnel","CrowdStrike"],"_cs_severities":["high"],"_cs_tags":["credential-access","mimikatz","memssp","windows"],"_cs_type":"advisory","_cs_vendors":["Elastic","Microsoft","SentinelOne","Crowdstrike"],"content_html":"\u003cp\u003eThis detection identifies the creation of the \u003ccode\u003emimilsa.log\u003c/code\u003e file, a default log generated by the Mimikatz \u003ccode\u003emisc::memssp\u003c/code\u003e module. The \u003ccode\u003emisc::memssp\u003c/code\u003e module injects a malicious Security Support Provider (SSP) into the Local Security Authority Subsystem Service (LSASS) process. This injected SSP logs credentials from subsequent logons to the compromised host, allowing attackers to capture sensitive information. The creation of this log file is a strong indicator of credential access attempts and the potential compromise of user accounts and system security. This rule is designed for data generated by Elastic Defend and also supports data from CrowdStrike, Microsoft Defender XDR, and SentinelOne Cloud Funnel.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker gains initial access to a Windows system (e.g., via phishing or exploiting a vulnerability).\u003c/li\u003e\n\u003cli\u003eThe attacker executes Mimikatz or a similar tool with the \u003ccode\u003emisc::memssp\u003c/code\u003e module.\u003c/li\u003e\n\u003cli\u003eMimikatz injects a malicious SSP library (e.g., \u003ccode\u003emimilib.dll\u003c/code\u003e) into the LSASS process (\u003ccode\u003elsass.exe\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe injected SSP hooks into the authentication process.\u003c/li\u003e\n\u003cli\u003eWhen users log on to the system, the SSP captures their credentials.\u003c/li\u003e\n\u003cli\u003eThe captured credentials are written to the \u003ccode\u003emimilsa.log\u003c/code\u003e file, typically located in \u003ccode\u003eC:\\Windows\\System32\\\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe attacker retrieves the \u003ccode\u003emimilsa.log\u003c/code\u003e file to obtain the captured credentials.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the stolen credentials to escalate privileges, move laterally within the network, and access sensitive resources.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eA successful Mimikatz MemSSP attack can lead to the compromise of user accounts, including those with administrative privileges. This allows attackers to gain unauthorized access to sensitive data, systems, and resources within the organization. Lateral movement becomes easier, potentially impacting a large number of systems. The compromised credentials can also be used for external attacks, such as gaining access to cloud services or other external resources.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eMimikatz Memssp Log File Detected\u003c/code\u003e to your SIEM and tune for your environment.\u003c/li\u003e\n\u003cli\u003eEnable Sysmon file creation logging to detect the creation of \u003ccode\u003emimilsa.log\u003c/code\u003e files.\u003c/li\u003e\n\u003cli\u003eInvestigate any alerts generated by the Sigma rule, focusing on the process that created the log file and any subsequent file access.\u003c/li\u003e\n\u003cli\u003eMonitor for the presence of \u003ccode\u003emimilib.dll\u003c/code\u003e and any LSA Security Packages registry modifications, as these may indicate persistent SSP installation.\u003c/li\u003e\n\u003cli\u003eReview and restrict interactive logons to high-value hosts to minimize the potential for credential theft.\u003c/li\u003e\n\u003cli\u003eInvestigate related alerts for the same \u003ccode\u003ehost.id\u003c/code\u003e in the last 48 hours covering delivery, privilege escalation, LSASS access, persistence, lateral movement, or additional credential access.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T17:00:00Z","date_published":"2024-01-03T17:00:00Z","id":"/briefs/2024-01-mimikatz-memssp-log/","summary":"This rule detects the creation of the default Mimikatz MemSSP credential log file, mimilsa.log, which is created after the misc::memssp module injects a malicious Security Support Provider into LSASS, potentially capturing credentials from subsequent logons.","title":"Mimikatz MemSSP Log File Detection","url":"https://feed.craftedsignal.io/briefs/2024-01-mimikatz-memssp-log/"}],"language":"en","title":"CraftedSignal Threat Feed — Memssp","version":"https://jsonfeed.org/version/1.1"}