{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/products/windows-auto-update-client/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["Windows Auto Update Client"],"_cs_severities":["medium"],"_cs_tags":["defense-evasion","execution","lolbas","windows"],"_cs_type":"advisory","_cs_vendors":["Microsoft"],"content_html":"\u003cp\u003eAttackers are abusing the Windows Update Auto Update Client (wuauclt.exe) to execute arbitrary code by loading malicious DLLs. This technique allows malicious actors to evade defenses by masquerading their activity as legitimate Windows processes. The abuse involves using specific command-line arguments with wuauclt.exe to load a DLL from a user-writable directory. This behavior has been observed in various attacks aimed at evading traditional security measures. This is an effective defense evasion and execution technique, allowing attackers to execute code while blending in with normal system processes, potentially bypassing application control and other security mechanisms.\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 through an unrelated method.\u003c/li\u003e\n\u003cli\u003eThe attacker places a malicious DLL in a directory writable by standard users, such as \u003ccode\u003eC:\\Users\\\u0026lt;username\u0026gt;\\\u003c/code\u003e, \u003ccode\u003eC:\\ProgramData\\\u003c/code\u003e, \u003ccode\u003eC:\\Windows\\Temp\\\u003c/code\u003e, or \u003ccode\u003eC:\\Windows\\Tasks\\\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe attacker executes \u003ccode\u003ewuauclt.exe\u003c/code\u003e with the arguments \u003ccode\u003e/RunHandlerComServer\u003c/code\u003e and \u003ccode\u003e/UpdateDeploymentProvider\u003c/code\u003e along with the path to the malicious DLL. For example: \u003ccode\u003ewuauclt.exe /RunHandlerComServer /UpdateDeploymentProvider /dll:\u0026lt;path_to_malicious_dll\u0026gt;\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003e\u003ccode\u003ewuauclt.exe\u003c/code\u003e loads the specified malicious DLL.\u003c/li\u003e\n\u003cli\u003eThe malicious DLL executes arbitrary code within the context of the \u003ccode\u003ewuauclt.exe\u003c/code\u003e process.\u003c/li\u003e\n\u003cli\u003eThe malicious code performs its intended actions, such as establishing persistence, communicating with a C2 server, or escalating privileges.\u003c/li\u003e\n\u003cli\u003eThe attacker may then use the compromised system as a foothold for lateral movement within the network.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation allows attackers to execute arbitrary code within a trusted Windows process, potentially bypassing security controls and making detection more difficult. While specific victim counts are unavailable, this technique can be used in targeted attacks against organizations where defense evasion is a priority for the adversary. Successful execution can lead to complete system compromise, data theft, or further malicious activities.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eImageLoad via Windows Update Auto Update Client\u003c/code\u003e to detect the execution of \u003ccode\u003ewuauclt.exe\u003c/code\u003e with suspicious arguments.\u003c/li\u003e\n\u003cli\u003eMonitor process creation events for \u003ccode\u003ewuauclt.exe\u003c/code\u003e with the arguments \u003ccode\u003e/RunHandlerComServer\u003c/code\u003e and \u003ccode\u003e/UpdateDeploymentProvider\u003c/code\u003e, focusing on DLL paths in user-writable directories.\u003c/li\u003e\n\u003cli\u003eEnable Sysmon process-creation and image-load logging to improve visibility into this type of attack.\u003c/li\u003e\n\u003cli\u003eAudit DLLs loaded by \u003ccode\u003ewuauclt.exe\u003c/code\u003e and investigate any unsigned or unexpected DLLs.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-04T12:00:00Z","date_published":"2024-01-04T12:00:00Z","id":"/briefs/2024-01-wuauclt-dll-load/","summary":"The Windows Update Auto Update Client (wuauclt.exe) is being abused to load arbitrary DLLs, a defense evasion technique where malicious activity blends with legitimate Windows software by using specific process arguments and placing DLLs in writable paths.","title":"Abuse of Windows Update Client for DLL Loading","url":"https://feed.craftedsignal.io/briefs/2024-01-wuauclt-dll-load/"}],"language":"en","title":"CraftedSignal Threat Feed — Windows Auto Update Client","version":"https://jsonfeed.org/version/1.1"}