CVE-2004-1337 in Linux
Summary
by MITRE
The POSIX Capability Linux Security Module (LSM) for Linux kernel 2.6 does not properly handle the credentials of a process that is launched before the module is loaded, which allows local users to gain privileges.
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Analysis
by VulDB Data Team • 08/02/2019
The vulnerability described in CVE-2004-1337 represents a critical security flaw within the Linux kernel's Linux Security Module framework, specifically affecting the POSIX Capability LSM implementation in kernel version 2.6. This issue stems from improper credential handling during the module loading process, creating a window of opportunity for privilege escalation attacks. The flaw occurs when processes are initiated before the LSM is fully loaded into the kernel, leaving their credentials unprocessed according to the security policies that the module would normally enforce. This represents a fundamental failure in the kernel's security initialization sequence where the system fails to properly validate or restrict the privileges of processes that existed prior to security module activation.
The technical root cause of this vulnerability lies in the timing dependency between process creation and security module initialization within the Linux kernel's security framework. When the POSIX Capability LSM loads into the kernel, it should enforce capability-based access controls on all processes, but due to the improper credential handling, processes that were already running when the module loaded retain their original privileges without proper security policy enforcement. This creates a persistent security gap where local attackers can exploit this timing window to elevate their privileges. The vulnerability is categorized under CWE-284, which addresses improper access control, specifically focusing on the inadequate privilege management during system initialization phases. This weakness allows attackers to manipulate process credentials in a way that bypasses the intended security boundaries that should be enforced by the LSM.
From an operational impact perspective, this vulnerability enables local users to escalate their privileges from standard user level to root access without requiring additional exploitation techniques. The attack vector is particularly concerning because it does not require network access or complex external conditions, making it easily exploitable within local system environments. Attackers can simply launch processes before the LSM loads and then leverage the module's subsequent loading to gain elevated privileges. This vulnerability directly maps to ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system configuration weaknesses. The impact extends beyond simple privilege escalation as it undermines the entire security model of the system, potentially allowing attackers to gain persistent access, modify system files, and compromise the integrity of the entire kernel security framework.
The mitigation strategies for this vulnerability require careful system administration and kernel management practices. System administrators should ensure that security modules are loaded as early as possible in the boot process, ideally before any user processes are initiated. Kernel updates and patches addressing this specific timing issue should be applied immediately to prevent exploitation. Additionally, implementing proper system hardening measures including disabling unnecessary services, restricting user privileges, and monitoring process creation patterns can help reduce the attack surface. Organizations should also consider implementing process monitoring solutions that can detect anomalous credential handling patterns and ensure that all processes are properly validated against security policies upon system initialization. The vulnerability highlights the importance of proper security module initialization order and demonstrates how timing dependencies in kernel security implementations can create exploitable conditions that persist until addressed through proper patching and system configuration management.