{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/ld_preload/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":["Linux"],"_cs_severities":["high"],"_cs_tags":["privilege-escalation","ld_preload","linux"],"_cs_type":"advisory","_cs_vendors":["Linux"],"content_html":"\u003cp\u003eThe LD_PRELOAD environment variable in Linux allows users to specify shared libraries that should be loaded before others when a program is executed. This functionality, while legitimate, can be abused by attackers to inject malicious code into processes, including those running with elevated privileges (e.g., setuid binaries). By crafting a malicious shared object and setting LD_PRELOAD to point to it, an attacker can hijack the execution flow of a vulnerable program. This technique is effective because the preloaded library's code will be executed before the main program's code. This can lead to complete system compromise if the hijacked process runs as root.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker identifies a setuid binary vulnerable to LD_PRELOAD exploitation.\u003c/li\u003e\n\u003cli\u003eThe attacker creates a malicious shared object (e.g., \u003ccode\u003eevil.so\u003c/code\u003e) containing code to escalate privileges, such as creating a new setuid root shell.\u003c/li\u003e\n\u003cli\u003eThe attacker sets the \u003ccode\u003eLD_PRELOAD\u003c/code\u003e environment variable to the path of the malicious shared object: \u003ccode\u003eexport LD_PRELOAD=/tmp/evil.so\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe attacker executes the vulnerable setuid binary.\u003c/li\u003e\n\u003cli\u003eThe dynamic linker (\u003ccode\u003eld-linux.so\u003c/code\u003e) loads the malicious shared object specified by \u003ccode\u003eLD_PRELOAD\u003c/code\u003e into the process's memory space before the intended libraries.\u003c/li\u003e\n\u003cli\u003eThe malicious shared object's constructor function (e.g., \u003ccode\u003e_init()\u003c/code\u003e) is executed, which performs actions like creating a new setuid root shell or modifying system files.\u003c/li\u003e\n\u003cli\u003eThe original setuid binary continues execution (if the attacker hasn't completely taken over).\u003c/li\u003e\n\u003cli\u003eThe attacker uses the newly created setuid root shell or modified system to gain complete control over the system.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation via LD_PRELOAD allows an attacker to gain root privileges on the affected Linux system. This allows them to read sensitive data, install malware, modify system configurations, and potentially use the compromised system as a staging point for lateral movement within a network. The scope of the impact depends on the attacker's objectives, but privilege escalation always leads to a severe breach of system security.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMonitor for the execution of setuid/setgid binaries with \u003ccode\u003eLD_PRELOAD\u003c/code\u003e set (see Sigma rule \u0026quot;Detect LD_PRELOAD Usage with setuid/setgid\u0026quot;).\u003c/li\u003e\n\u003cli\u003eImplement file integrity monitoring for system binaries and libraries to detect unauthorized modifications (implement using file_event logs).\u003c/li\u003e\n\u003cli\u003eRestrict the use of \u003ccode\u003eLD_PRELOAD\u003c/code\u003e where possible, especially for privileged processes.\u003c/li\u003e\n\u003cli\u003eAudit setuid/setgid binaries for vulnerabilities that could be exploited via \u003ccode\u003eLD_PRELOAD\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026quot;Detect Suspicious Shared Object Loading via LD_PRELOAD\u0026quot; to identify potential malicious library injections.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T12:00:00Z","date_published":"2024-01-03T12:00:00Z","id":"https://feed.craftedsignal.io/briefs/2024-01-ld-preload-privilege-escalation/","summary":"Attackers can exploit the LD_PRELOAD environment variable on Linux systems to inject malicious shared objects into privileged processes, leading to arbitrary code execution and privilege escalation.","title":"Linux Privilege Escalation via LD_PRELOAD Shared Object Modification","url":"https://feed.craftedsignal.io/briefs/2024-01-ld-preload-privilege-escalation/"}],"language":"en","title":"CraftedSignal Threat Feed - Ld_preload","version":"https://jsonfeed.org/version/1.1"}