CVE-2010-4164 in Linux
Summary
by MITRE
Multiple integer underflows in the x25_parse_facilities function in net/x25/x25_facilities.c in the Linux kernel before 2.6.36.2 allow remote attackers to cause a denial of service (system crash) via malformed X.25 (1) X25_FAC_CLASS_A, (2) X25_FAC_CLASS_B, (3) X25_FAC_CLASS_C, or (4) X25_FAC_CLASS_D facility data, a different vulnerability than CVE-2010-3873.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/07/2021
The vulnerability identified as CVE-2010-4164 represents a critical integer underflow condition within the Linux kernel's X.25 protocol implementation, specifically affecting the x25_parse_facilities function in net/x25/x25_facilities.c. This flaw exists in kernel versions prior to 2.6.36.2 and enables remote attackers to trigger system crashes through carefully crafted malformed X.25 facility data. The vulnerability impacts four distinct X.25 facility classes namely A, B, C, and D, each representing different communication parameters and capabilities within the X.25 network protocol framework. The integer underflow occurs when processing facility data structures that define connection parameters and service classes, creating conditions where arithmetic operations result in values that fall below the minimum representable integer, leading to unpredictable behavior and system instability.
The technical nature of this vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations. The flaw manifests when the kernel processes incoming X.25 facility data without proper validation of integer values, particularly concerning length fields and parameter sizes within the facility data structures. Attackers can exploit this by sending specially crafted X.25 packets containing malformed facility information that, when parsed by the vulnerable kernel function, causes integer underflow conditions. These underflows can lead to buffer overflows, memory corruption, or other exploitable conditions that ultimately result in system crashes or denial of service scenarios. The vulnerability is particularly concerning because X.25 protocol support is often found in legacy network infrastructure and specialized communication systems where kernel updates may be delayed or restricted.
From an operational impact perspective, this vulnerability creates significant risk for systems relying on X.25 networking protocols, particularly those in industrial control systems, telecommunications infrastructure, or legacy network environments where the kernel cannot be easily updated. The remote exploitation capability means that attackers can trigger system crashes from outside the local network, potentially affecting critical infrastructure communications. The denial of service impact can be severe as X.25 connections may be used for essential network services, and system crashes can lead to complete service disruption. According to ATT&CK framework category T1499, this vulnerability maps to the disruption of services through system resource consumption or manipulation, specifically targeting network protocol stack implementations. The attack surface is broad as any system that processes X.25 facility data and runs vulnerable kernel versions is at risk, including routers, switches, and specialized network equipment that may be running embedded Linux systems with older kernel versions.
Mitigation strategies for CVE-2010-4164 primarily focus on kernel version updates to 2.6.36.2 or later, which contain the necessary patches addressing the integer underflow conditions in the x25_parse_facilities function. Organizations should prioritize updating their kernel versions, particularly in environments where X.25 protocol support is active or where legacy systems may be exposed to network traffic. Network segmentation and firewall rules can help limit exposure by blocking X.25 traffic to systems that do not require it, reducing the attack surface. Additionally, implementing intrusion detection systems that can identify malformed X.25 facility data patterns may provide early warning of exploitation attempts. For systems where kernel updates are not immediately possible, administrators should consider disabling X.25 protocol support entirely if the functionality is not required, as this eliminates the attack vector entirely. The vulnerability demonstrates the importance of proper input validation and integer handling in kernel space code, highlighting the need for comprehensive security testing of protocol implementations. Organizations should also review their patch management processes to ensure rapid deployment of security updates, particularly for critical infrastructure components that may be running older kernel versions due to compatibility or stability concerns.