CVE-2005-2555 in Linux
Summary
by MITRE
Linux kernel 2.6.x does not properly restrict socket policy access to users with the CAP_NET_ADMIN capability, which could allow local users to conduct unauthorized activities via (1) ipv4/ip_sockglue.c and (2) ipv6/ipv6_sockglue.c.
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Analysis
by VulDB Data Team • 07/04/2019
The vulnerability described in CVE-2005-2555 represents a critical privilege escalation flaw within the Linux kernel version 2.6.x series that specifically targets socket policy access controls. This issue stems from improper enforcement of capabilities within the network subsystem, creating a pathway for local attackers to bypass security restrictions that should normally prevent unauthorized access to socket operations. The vulnerability affects both ipv4 and ipv6 network protocol implementations, making it particularly dangerous as it impacts the fundamental networking capabilities of the operating system. The flaw manifests in the kernel's handling of the CAP_NET_ADMIN capability, which is designed to grant administrative privileges for network operations but fails to properly enforce access restrictions in socket policy contexts.
The technical implementation of this vulnerability occurs in two primary kernel source files: ipv4/ip_sockglue.c and ipv6/ipv6_sockglue.c. These files contain the socket glue code responsible for managing network socket operations and policy enforcement. The flaw arises when the kernel processes socket policy requests where users with CAP_NET_ADMIN capability can manipulate socket parameters in ways that should be restricted. This improper access control allows local users to potentially modify socket configurations, access restricted network resources, or conduct unauthorized network activities that would normally be prevented by proper capability checking mechanisms. The vulnerability specifically exploits the lack of proper validation when processing socket policy operations, enabling attackers to escalate their privileges or bypass network security controls.
The operational impact of this vulnerability is significant for any system running Linux kernel 2.6.x, particularly those with multiple local users or systems where users might have limited privileges but still require network administration capabilities. Local users who possess the CAP_NET_ADMIN capability can leverage this flaw to conduct unauthorized activities including but not limited to network packet manipulation, socket configuration changes, and potentially gaining additional privileges within the system. The implications extend beyond simple network access as the ability to manipulate socket policies can lead to more complex attacks such as network reconnaissance, traffic interception, or even system compromise through exploitation of other network-based vulnerabilities. This vulnerability essentially undermines the principle of least privilege by allowing users with specific administrative capabilities to perform operations that should remain restricted.
Mitigation strategies for CVE-2005-2555 should focus on immediate kernel updates to versions that address the improper capability checks in socket policy handling. System administrators should ensure that all Linux systems running kernel 2.6.x are updated to patched versions that properly enforce access controls in both ipv4 and ipv6 socket implementations. Additionally, organizations should review and restrict the assignment of CAP_NET_ADMIN capability to only those users who absolutely require it for legitimate administrative tasks. The vulnerability aligns with CWE-284 which addresses improper access control in software systems, and relates to ATT&CK technique T1068 which covers privilege escalation through local exploitation. Regular security audits should verify that socket policy operations are properly restricted and that users with elevated capabilities cannot abuse their privileges to access restricted network resources. Organizations should also implement monitoring for unusual socket configuration changes or network policy modifications that could indicate exploitation attempts.