{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/startup-hook/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Python"],"_cs_severities":["medium"],"_cs_tags":["persistence","python","startup-hook","linux"],"_cs_type":"advisory","_cs_vendors":["Python"],"content_html":"\u003cp\u003eThis brief covers the exploitation of Python startup hooks for persistence on Linux systems. Attackers can modify or create \u003ccode\u003esitecustomize.py\u003c/code\u003e and \u003ccode\u003eusercustomize.py\u003c/code\u003e files, which Python automatically executes on startup, allowing for arbitrary code execution. This technique is valuable for adversaries seeking to maintain covert access and execute commands without relying on traditional persistence mechanisms. The Elastic detection rule focuses on identifying unauthorized creation or modification of these files in system-wide, user-specific, and virtual environment locations, while excluding known benign processes like package managers and system update tools. Detecting these malicious modifications is crucial for defenders to identify and prevent unauthorized persistence mechanisms.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker gains initial access to a Linux system through vulnerabilities, compromised credentials, or other methods.\u003c/li\u003e\n\u003cli\u003eThe attacker identifies locations where Python's \u003ccode\u003esitecustomize.py\u003c/code\u003e or \u003ccode\u003eusercustomize.py\u003c/code\u003e files are loaded. These locations include system-wide directories (\u003ccode\u003e/usr/lib/python*/sitecustomize.py\u003c/code\u003e) and user-specific configurations (\u003ccode\u003e/home/*/.config/python/usercustomize.py\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe attacker creates or modifies the target \u003ccode\u003esitecustomize.py\u003c/code\u003e or \u003ccode\u003eusercustomize.py\u003c/code\u003e file with malicious Python code. The injected code could download and execute a payload, establish a reverse shell, or perform other malicious activities.\u003c/li\u003e\n\u003cli\u003eThe attacker ensures the modified files are in the correct locations with the appropriate permissions.\u003c/li\u003e\n\u003cli\u003eWhen a user or system process executes Python, the malicious code within \u003ccode\u003esitecustomize.py\u003c/code\u003e or \u003ccode\u003eusercustomize.py\u003c/code\u003e is automatically executed.\u003c/li\u003e\n\u003cli\u003eThe injected code establishes a persistent connection to a command-and-control (C2) server, allowing the attacker to remotely control the compromised system.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the established connection to perform further reconnaissance, lateral movement, or data exfiltration.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation allows attackers to establish persistent access to compromised systems. By hijacking Python startup, attackers can execute arbitrary code each time Python is run, potentially leading to data theft, system compromise, or further propagation of malware. While the source does not specify a precise number of victims, the widespread use of Python makes this technique applicable across various sectors, including software development, data science, and system administration. If successful, attackers can maintain a long-term presence on the affected systems, posing a significant threat to data confidentiality and system integrity.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026quot;Linux Python Startup Hook File Creation\u0026quot; to your SIEM and tune for your environment to detect malicious file creation events in Python's site-package directories.\u003c/li\u003e\n\u003cli\u003eMonitor process creation events for Python interpreters executing with modified \u003ccode\u003esitecustomize.py\u003c/code\u003e or \u003ccode\u003eusercustomize.py\u003c/code\u003e files (process_creation log source).\u003c/li\u003e\n\u003cli\u003eRegularly audit the contents of \u003ccode\u003esitecustomize.py\u003c/code\u003e and \u003ccode\u003eusercustomize.py\u003c/code\u003e files on critical systems to identify unauthorized modifications.\u003c/li\u003e\n\u003cli\u003eEnable Elastic Defend to collect file creation events and process metadata as required by the provided detection rules.\u003c/li\u003e\n\u003cli\u003eUpdate the exclusion list in the provided Sigma rule to include any legitimate processes in your environment that modify \u003ccode\u003esitecustomize.py\u003c/code\u003e or \u003ccode\u003eusercustomize.py\u003c/code\u003e.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T14:30:00Z","date_published":"2024-01-03T14:30:00Z","id":"https://feed.craftedsignal.io/briefs/2024-01-python-startup-hook-persistence/","summary":"Attackers can exploit Python's sitecustomize.py and usercustomize.py files for persistence by injecting malicious code, allowing them to execute arbitrary commands upon Python startup.","title":"Python Site or User Customize File Creation for Persistence","url":"https://feed.craftedsignal.io/briefs/2024-01-python-startup-hook-persistence/"}],"language":"en","title":"CraftedSignal Threat Feed - Startup-Hook","version":"https://jsonfeed.org/version/1.1"}