CVE-2011-0006 in Linux
Summary
by MITRE
The ima_lsm_rule_init function in security/integrity/ima/ima_policy.c in the Linux kernel before 2.6.37, when the Linux Security Modules (LSM) framework is disabled, allows local users to bypass Integrity Measurement Architecture (IMA) rules in opportunistic circumstances by leveraging an administrator s addition of an IMA rule for LSM.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/05/2021
The vulnerability described in CVE-2011-0006 represents a critical flaw in the Linux kernel's Integrity Measurement Architecture implementation that specifically affects systems running kernel versions prior to 2.6.37. This issue arises from a design oversight in the ima_lsm_rule_init function located within the security/integrity/ima/ima_policy.c file, where the kernel fails to properly validate IMA rule enforcement when the Linux Security Modules framework is disabled. The flaw creates a security bypass condition that allows local attackers to circumvent integrity measurements that should otherwise be enforced by IMA policies, potentially compromising the system's security posture and integrity verification mechanisms.
The technical root cause of this vulnerability stems from improper handling of IMA policy initialization when LSM functionality is not active. When administrators configure IMA rules specifically designed for LSM integration, the kernel's initialization process does not adequately account for scenarios where LSM is disabled. This creates a conditional execution path where IMA rules intended to enforce security policies can be bypassed due to the absence of proper validation checks. The vulnerability manifests in opportunistic circumstances, meaning it only presents a risk under specific conditions where an administrator has added IMA rules that reference LSM functionality while the LSM framework itself remains disabled. This creates a dangerous inconsistency in the kernel's security enforcement model, where the presence of certain IMA rules inadvertently weakens the overall security posture rather than strengthening it.
From an operational impact perspective, this vulnerability enables local users to bypass critical integrity measurement controls that are fundamental to the IMA framework's purpose. The ability to circumvent these measurements undermines the core security principle of ensuring that system files and binaries maintain their expected integrity throughout the system's operation. Attackers could potentially modify critical system components without triggering IMA alerts or enforcement mechanisms, effectively allowing them to compromise system integrity without detection. This vulnerability directly impacts the Confidentiality, Integrity, and Availability (CIA) triad by weakening the system's ability to detect unauthorized modifications and maintain secure state enforcement. The operational risk is particularly concerning in environments where IMA is deployed as part of a comprehensive security strategy, as it essentially renders certain IMA protections ineffective.
The vulnerability aligns with CWE-284 Access Control Issues, specifically addressing inadequate access control enforcement within the kernel's security subsystem. It also maps to ATT&CK technique T1566.002 for credential access and T1059.001 for command and scripting interpreter, as local users could exploit this weakness to execute malicious code or manipulate system integrity checks. Organizations implementing IMA-based security controls should consider this vulnerability as a critical risk that could undermine their entire integrity measurement strategy, particularly in environments where kernel-level security is paramount. The patch for this vulnerability involves ensuring proper validation of IMA rule initialization regardless of LSM framework status, preventing the bypass condition that allows local users to circumvent integrity measurements.
Mitigation strategies should include immediate kernel upgrades to version 2.6.37 or later, where the vulnerability has been addressed through proper initialization validation. Administrators should also review existing IMA policies to ensure that rules do not create inconsistent security states when LSM is disabled, and consider implementing additional monitoring controls to detect potential exploitation attempts. Organizations should conduct comprehensive security assessments to identify systems running vulnerable kernel versions and prioritize patching efforts accordingly. The vulnerability demonstrates the importance of proper kernel security validation and highlights the need for thorough testing of security subsystems under various configuration states to prevent unintended security bypass conditions.