{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/mountvol/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["Splunk Enterprise","Splunk Enterprise Security","Splunk Cloud"],"_cs_severities":["high"],"_cs_tags":["efi","mountvol","windows","persistence","defense-evasion"],"_cs_type":"advisory","_cs_vendors":["Splunk"],"content_html":"\u003cp\u003eThis detection identifies attempts to mount the EFI volume on Windows systems using the \u003ccode\u003emountvol.exe\u003c/code\u003e utility. The EFI system partition (ESP) is a special partition crucial for system booting. Unauthorized modification of the ESP can compromise system integrity, allowing attackers to modify the system on boot. This technique is associated with attacks like PKFail. The scope of this threat involves potential compromise of Windows systems and the ability to modify the boot process for malicious purposes, affecting system integrity and security. The detection leverages process monitoring to identify suspicious use of \u003ccode\u003emountvol.exe\u003c/code\u003e.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker gains initial access to the system, potentially through social engineering or exploitation of a vulnerability.\u003c/li\u003e\n\u003cli\u003eThe attacker executes \u003ccode\u003emountvol.exe\u003c/code\u003e with the \u003ccode\u003e-S\u003c/code\u003e or \u003ccode\u003e/S\u003c/code\u003e parameter to mount the EFI volume.\u003c/li\u003e\n\u003cli\u003eThe attacker gains write access to the EFI system partition.\u003c/li\u003e\n\u003cli\u003eThe attacker modifies bootloaders or other EFI executables.\u003c/li\u003e\n\u003cli\u003eThe attacker may install malicious drivers or backdoors into the EFI partition.\u003c/li\u003e\n\u003cli\u003eThe system is rebooted, triggering the malicious code within the EFI partition.\u003c/li\u003e\n\u003cli\u003eThe malicious code compromises the operating system during the boot process.\u003c/li\u003e\n\u003cli\u003eThe attacker achieves persistence and control over the system.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation can lead to persistent malware installation, allowing attackers to maintain control over the compromised system even after reboots or OS reinstalls. The impact includes potential data theft, system corruption, and the ability to install rootkits that are difficult to detect. If successful, the attacker can gain complete control over the system.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect EFI Volume Mount via Mountvol\u003c/code\u003e to your SIEM and tune for your environment.\u003c/li\u003e\n\u003cli\u003eMonitor process execution logs for instances of \u003ccode\u003emountvol.exe\u003c/code\u003e being executed with the \u003ccode\u003e-S\u003c/code\u003e or \u003ccode\u003e/S\u003c/code\u003e parameters.\u003c/li\u003e\n\u003cli\u003eInvestigate any alerts generated by the Sigma rule, paying close attention to the parent processes and user accounts involved.\u003c/li\u003e\n\u003cli\u003eImplement strict access controls on the EFI system partition to prevent unauthorized modifications.\u003c/li\u003e\n\u003cli\u003eRegularly scan systems for signs of EFI-based rootkits or other malicious modifications.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T15:00:00Z","date_published":"2024-01-03T15:00:00Z","id":"/briefs/2024-01-03-efi-volume-mount/","summary":"Detection of attempts to mount the EFI volume on Windows systems using mountvol.exe, potentially leading to system compromise.","title":"Windows EFI Volume Mount Attempt via Mountvol","url":"https://feed.craftedsignal.io/briefs/2024-01-03-efi-volume-mount/"}],"language":"en","title":"CraftedSignal Threat Feed — Mountvol","version":"https://jsonfeed.org/version/1.1"}