CVE-2009-0876 in xVM VirtualBox
Summary
by MITRE
Sun xVM VirtualBox 2.0.0, 2.0.2, 2.0.4, 2.0.6r39760, 2.1.0, 2.1.2, and 2.1.4r42893 on Linux allows local users to gain privileges via a hardlink attack, which preserves setuid/setgid bits on Linux, related to DT_RPATH:$ORIGIN.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability described in CVE-2009-0876 represents a critical privilege escalation flaw affecting multiple versions of Sun xVM VirtualBox virtualization software running on Linux systems. This issue specifically targets the handling of dynamic library loading mechanisms within the virtualization environment, creating a pathway for local attackers to elevate their privileges from standard user level to root access. The vulnerability stems from the improper management of the DT_RPATH dynamic tag combined with the $ORIGIN token, which allows attackers to manipulate the library loading process in ways that preserve setuid/setgid permissions during the attack execution.
The technical root cause of this vulnerability lies in how VirtualBox handles dynamic library resolution when the DT_RPATH dynamic tag contains the $ORIGIN token, which refers to the directory containing the executable being run. When a malicious user creates a hardlink to a vulnerable VirtualBox component and places a malicious library in a directory that matches the $ORIGIN path, the system's dynamic loader will preferentially load the attacker-controlled library instead of the legitimate one. This behavior is particularly dangerous because it occurs within the context of setuid/setgid binaries, where the preservation of these bits during the hardlink attack allows the malicious library to execute with elevated privileges. The flaw is fundamentally a result of insufficient validation of library paths and improper handling of the dynamic linking process in the virtualization environment.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system control through a relatively straightforward local attack vector. Attackers can exploit this vulnerability by creating hardlinks in strategic locations and manipulating the library loading sequence to inject malicious code that executes with root privileges. This attack does not require network access or remote exploitation capabilities, making it particularly dangerous as it can be executed entirely from within the local system. The vulnerability affects all listed versions of VirtualBox, indicating it was a persistent flaw that required multiple releases to address, and it demonstrates the complexity of managing dynamic library loading in virtualized environments where multiple security contexts must be properly maintained.
The security implications of this vulnerability align with CWE-428, which addresses "Unquoted Search Path or Element," and relates to the broader category of privilege escalation vulnerabilities. This flaw also connects to ATT&CK technique T1068, which covers "Local Privilege Escalation," and specifically demonstrates how attackers can exploit weaknesses in system call handling and library loading mechanisms. Organizations running affected VirtualBox versions face significant risk, as this vulnerability can be exploited by any local user to gain root access, potentially leading to complete system compromise, data exfiltration, and persistent access to network resources. The vulnerability represents a fundamental flaw in how the virtualization software manages dynamic library loading while maintaining security contexts, highlighting the importance of proper privilege management in virtualized environments.
Mitigation strategies for this vulnerability require immediate patching of affected VirtualBox versions to address the dynamic library loading behavior and ensure proper validation of library paths. System administrators should also implement additional security controls such as disabling unnecessary setuid/setgid binaries, monitoring for suspicious hardlink creation activities, and implementing proper file system permissions to limit the ability of local users to manipulate critical system files. The vulnerability underscores the importance of proper sandboxing in virtualization environments and demonstrates why dynamic library loading mechanisms must be carefully designed to prevent attackers from manipulating the execution context of privileged processes. Organizations should also consider implementing automated patch management systems to ensure timely remediation of similar vulnerabilities in virtualization software and other system components.