CVE-2011-2497 in Linux
Summary
by MITRE
Integer underflow in the l2cap_config_req function in net/bluetooth/l2cap_core.c in the Linux kernel before 3.0 allows remote attackers to cause a denial of service (heap memory corruption) or possibly have unspecified other impact via a small command-size value within the command header of a Logical Link Control and Adaptation Protocol (L2CAP) configuration request, leading to a buffer overflow.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/18/2021
The vulnerability identified as CVE-2011-2497 represents a critical integer underflow flaw within the Linux kernel's Bluetooth implementation, specifically affecting the l2cap_config_req function in the net/bluetooth/l2cap_core.c source file. This issue exists in kernel versions prior to 3.0 and demonstrates a fundamental flaw in input validation and arithmetic handling that can be exploited by remote attackers to compromise system stability and potentially execute arbitrary code. The vulnerability manifests when processing Logical Link Control and Adaptation Protocol configuration requests, which are essential components of Bluetooth communication protocols that establish and maintain connections between devices.
The technical root cause of this vulnerability stems from improper handling of command-size values within L2CAP configuration request headers. When a remote attacker crafts a malicious L2CAP packet containing a deliberately small command-size value, the kernel's l2cap_config_req function fails to properly validate this input before performing arithmetic operations. This integer underflow condition occurs when the system attempts to subtract a larger value from a smaller one, resulting in an unexpectedly large positive integer value that exceeds the expected range. The flaw creates a scenario where heap memory allocation calculations become corrupted, leading to memory corruption that can result in system crashes or unpredictable behavior. This type of vulnerability falls under CWE-191 Integer Underflow (Wrap or Wraparound) and represents a classic example of how improper input validation can lead to memory safety issues.
The operational impact of CVE-2011-2497 extends beyond simple denial of service scenarios, as the heap memory corruption can potentially enable more sophisticated attacks depending on the system configuration and attack surface. Remote attackers can exploit this vulnerability without requiring authentication or local access, making it particularly dangerous in environments where Bluetooth connectivity is exposed to untrusted networks or devices. The potential for unspecified other impacts suggests that in certain configurations or under specific conditions, this vulnerability could allow for privilege escalation or code execution within the kernel space. This aligns with ATT&CK technique T1068, which covers the exploitation of privilege escalation vulnerabilities, and demonstrates how kernel-level flaws can provide attackers with elevated system access.
Mitigation strategies for CVE-2011-2497 primarily focus on kernel version updates and proper input validation measures. System administrators should immediately upgrade to Linux kernel version 3.0 or later, where this vulnerability has been addressed through proper integer overflow checking and input validation mechanisms. Additionally, network administrators should implement Bluetooth access controls and restrict Bluetooth connectivity to trusted devices only, particularly in environments where untrusted parties might have physical access to Bluetooth-enabled systems. The fix implemented in kernel 3.0 involves adding proper bounds checking for command-size values and ensuring that arithmetic operations maintain valid integer ranges before memory allocation occurs. Organizations should also consider implementing network monitoring solutions that can detect anomalous Bluetooth traffic patterns that might indicate exploitation attempts, as this vulnerability can be used both for denial of service attacks and as a stepping stone for more advanced compromise techniques.