{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/xll/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["Excel","Splunk Enterprise","Splunk Enterprise Security","Splunk Cloud"],"_cs_severities":["high"],"_cs_tags":["xll","excel","file_creation","endpoint"],"_cs_type":"advisory","_cs_vendors":["Microsoft","Splunk"],"content_html":"\u003cp\u003eAttackers are known to leverage malicious Excel add-in files (.xll) to execute arbitrary code on a victim\u0026rsquo;s machine. These files, when opened by Excel, can load and run malicious code embedded within them. The technique is often seen in spearphishing campaigns where a user is tricked into opening the malicious XLL file. This detection focuses on identifying XLL file creation events occurring outside of standard application or add-in directories, which is a strong indicator of potentially malicious activity. The goal is to detect the initial stage of the attack, preventing further exploitation.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eA malicious XLL file is delivered to the victim, often via spearphishing attachment or download.\u003c/li\u003e\n\u003cli\u003eThe victim opens the XLL file, potentially after being socially engineered.\u003c/li\u003e\n\u003cli\u003eExcel loads the XLL file.\u003c/li\u003e\n\u003cli\u003eThe XLL file executes malicious code.\u003c/li\u003e\n\u003cli\u003eThe malicious code may establish persistence through registry modifications or scheduled tasks.\u003c/li\u003e\n\u003cli\u003eThe attacker gains initial access to the system.\u003c/li\u003e\n\u003cli\u003eThe attacker executes arbitrary commands, downloads additional payloads, or moves laterally within the network.\u003c/li\u003e\n\u003cli\u003eThe attacker achieves their final objective, such as data exfiltration or ransomware deployment.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation can lead to complete system compromise, potentially affecting all data and applications on the compromised machine. This can lead to data breaches, financial loss, and reputational damage. Organizations in any sector are vulnerable, especially those with employees who handle email and Excel documents. The impact includes potential remote code execution, data theft, and lateral movement within the network.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eEnable Sysmon Event ID 11 (FileCreate) logging to capture file creation events on endpoints to support the provided rules.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eXLL File Creation Outside of Typical Locations\u003c/code\u003e to your SIEM and tune for your environment.\u003c/li\u003e\n\u003cli\u003eInvestigate any identified events to determine whether the XLL file is malicious.\u003c/li\u003e\n\u003cli\u003eEducate users about the risks of opening unsolicited attachments and enabling macros.\u003c/li\u003e\n\u003cli\u003eReview and restrict Excel add-in installation policies to prevent unauthorized installations.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T12:00:00Z","date_published":"2024-01-03T12:00:00Z","id":"/briefs/2024-01-xll-file-creation/","summary":"The creation of an XLL file outside of typical locations can indicate an attempt to abuse Excel COM objects to load and execute a malicious XLL payload, often used in spearphishing attacks to achieve remote code execution.","title":"Detects Windows XLL File Creation Outside of Typical Location","url":"https://feed.craftedsignal.io/briefs/2024-01-xll-file-creation/"}],"language":"en","title":"CraftedSignal Threat Feed — Xll","version":"https://jsonfeed.org/version/1.1"}