CVE-2009-3280 in Linux
Summary
by MITRE
Integer signedness error in the find_ie function in net/wireless/scan.c in the cfg80211 subsystem in the Linux kernel before 2.6.31.1-rc1 allows remote attackers to cause a denial of service (soft lockup) via malformed packets.
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Analysis
by VulDB Data Team • 04/14/2019
The vulnerability described in CVE-2009-3280 represents a critical integer signedness error within the Linux kernel's wireless subsystem, specifically in the cfg80211 framework that manages wireless device configurations and scanning operations. This flaw exists in the find_ie function located in net/wireless/scan.c, which is responsible for parsing information elements within wireless management frames. The issue arises from improper handling of signed versus unsigned integer comparisons during the parsing of wireless packet structures, creating a condition where maliciously crafted wireless frames can trigger unexpected behavior in the kernel's wireless scanning mechanism.
The technical implementation of this vulnerability stems from a fundamental flaw in how the kernel processes wireless packet information elements during scan operations. When the find_ie function encounters malformed wireless frames, the signedness error causes incorrect loop boundary calculations or buffer offset computations, leading to a scenario where the kernel enters an infinite loop or excessive processing state. This occurs because unsigned integer values from packet headers are incorrectly interpreted as signed integers during comparison operations, causing the scanning loop to continue indefinitely or consume excessive CPU resources. The vulnerability specifically affects Linux kernel versions prior to 2.6.31.1-rc1, indicating that this was a well-known issue that required specific kernel version updates to resolve.
The operational impact of this vulnerability manifests as a denial of service condition that can result in system soft lockups, where the affected kernel subsystem becomes unresponsive and requires manual intervention or system reboot to restore normal operation. Remote attackers can exploit this vulnerability by transmitting specially crafted wireless management frames that contain malformed information elements, triggering the integer signedness error in the kernel's wireless scanning code. The soft lockup condition essentially renders the wireless subsystem unusable while potentially affecting overall system stability, as the kernel thread responsible for wireless operations becomes stuck in an infinite processing loop. This type of denial of service can be particularly problematic in network infrastructure devices, access points, or wireless routers that rely on continuous wireless scanning functionality.
From a cybersecurity perspective, this vulnerability aligns with CWE-191, which specifically addresses integer underflow and overflow conditions, and can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. The vulnerability demonstrates how seemingly minor programming errors in kernel subsystems can result in significant operational impacts, particularly in wireless network environments where continuous scanning is essential for network management and client association. Organizations deploying Linux-based wireless infrastructure should prioritize patching to kernel versions 2.6.31.1-rc1 or later, as this vulnerability represents a clear indication of inadequate input validation in critical kernel components. The fix typically involves correcting the integer signedness handling in the affected function to ensure proper comparison operations between unsigned packet header values and signed loop counters. Additionally, network administrators should implement monitoring solutions to detect unusual wireless traffic patterns that might indicate exploitation attempts, while maintaining up-to-date kernel security patches to prevent similar vulnerabilities from affecting their wireless infrastructure deployments.