CVE-2005-3753 in Linux
Summary
by MITRE
Linux kernel before after 2.6.12 and before 2.6.13.1 might allow attackers to cause a denial of service (Oops) via certain IPSec packets that cause alignment problems in standard multi-block cipher processors. NOTE: it is not clear whether this issue can be triggered by an attacker.
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Analysis
by VulDB Data Team • 04/13/2019
The vulnerability identified as CVE-2005-3753 represents a critical denial of service flaw affecting Linux kernel versions prior to 2.6.13.1, specifically impacting systems running kernel versions before 2.6.12. This weakness manifests through improper handling of IPSec packets that create alignment issues within multi-block cipher processors, potentially leading to system crashes or oops conditions. The vulnerability's classification as a potential remote attack vector stems from its ability to be triggered by specially crafted IPSec traffic, though the exact exploitability remains somewhat uncertain as noted in the original description.
The technical root cause of this vulnerability lies in the kernel's cryptographic subsystem's handling of IPSec packet processing, particularly when dealing with multi-block cipher algorithms. When certain IPSec packets arrive with specific alignment characteristics that do not conform to the expected memory boundaries for cipher operations, the kernel's cryptographic processing routines fail to properly manage these alignment discrepancies. This misalignment causes the processor to encounter invalid memory access patterns during cipher block operations, resulting in kernel oops conditions that ultimately lead to system instability and potential denial of service. The issue is particularly pronounced on processors that require strict memory alignment for optimal performance in multi-block cipher operations, where misaligned data access can cause processor exceptions or system crashes.
From an operational perspective, this vulnerability presents a significant risk to systems that rely on IPSec for network security, particularly in enterprise environments where IPSec tunnels are commonly deployed for secure communications. The potential for remote exploitation means that an attacker positioned on the network can potentially disrupt services by sending specifically crafted IPSec packets designed to trigger the alignment fault. However, the uncertainty regarding exploitability suggests that successful exploitation might require specific conditions or might be more difficult to achieve than typical denial of service vulnerabilities. The impact extends beyond simple service disruption, as kernel oops conditions can lead to system crashes, requiring manual intervention to restore normal operations and potentially causing extended downtime in mission-critical systems.
The vulnerability's relationship to established security frameworks reveals its alignment with CWE-129, which addresses improper handling of buffer overflows or memory access violations, and CWE-131, concerning improper handling of memory alignment issues. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and denial of service, though the specific technique of process injection or privilege escalation is not directly applicable. The attack surface is primarily through network-based IPSec packet processing, making it relevant to T1071.004 for application layer protocol and T1499.004 for network denial of service. Organizations should consider implementing network segmentation and monitoring to detect unusual IPSec traffic patterns that might indicate exploitation attempts, while also maintaining awareness of the specific kernel version requirements for mitigation.
Mitigation strategies should focus on immediate kernel upgrades to versions 2.6.13.1 or later, which contain the necessary patches to address the alignment handling issues in the cryptographic subsystem. System administrators should also implement network monitoring solutions capable of detecting and alerting on anomalous IPSec packet patterns that might indicate exploitation attempts. Additional defensive measures include configuring IPSec policies to minimize exposure to potentially malicious traffic, implementing firewall rules to restrict IPSec traffic from untrusted sources, and establishing robust system monitoring to detect kernel oops conditions that could indicate exploitation. Organizations should also consider maintaining detailed logs of cryptographic operations and system stability metrics to aid in incident response should the vulnerability be successfully exploited, while ensuring that all systems undergo regular security assessments to identify similar alignment-related vulnerabilities in other cryptographic components.