CVE-2012-2942 in HAProxy
Summary
by MITRE
Buffer overflow in the trash buffer in the header capture functionality in HAProxy before 1.4.21, when global.tune.bufsize is set to a value greater than the default and header rewriting is enabled, allows remote attackers to cause a denial of service and possibly execute arbitrary code via unspecified vectors.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/03/2021
The vulnerability identified as CVE-2012-2942 represents a critical buffer overflow condition within HAProxy's header capture functionality that emerged in versions prior to 1.4.21. This flaw specifically manifests when the global.tune.bufsize parameter is configured to exceed default settings while header rewriting operations are active, creating a dangerous scenario where remote attackers can exploit the system's memory management mechanisms. The buffer overflow occurs in the trash buffer component responsible for handling header captures, making it particularly dangerous as it operates within the core processing pathways of the load balancing system. The vulnerability's exploitation potential extends beyond simple denial of service to include possible arbitrary code execution, significantly elevating its threat level in production environments.
The technical implementation of this vulnerability stems from inadequate bounds checking within HAProxy's memory allocation routines when processing HTTP headers. When global.tune.bufsize is increased beyond standard parameters, the system allocates memory buffers that do not properly validate input lengths against allocated space. The header capture functionality, which operates in the trash buffer context, fails to implement proper overflow protection mechanisms, allowing malicious input data to overwrite adjacent memory locations. This memory corruption can occur during the processing of HTTP headers where header rewriting is enabled, creating a pathway for attackers to manipulate the program's execution flow. The vulnerability operates at the application layer and can be triggered through crafted HTTP requests that contain oversized header values, making it particularly effective against systems that process large volumes of HTTP traffic.
The operational impact of CVE-2012-2942 is severe and multifaceted, affecting both availability and confidentiality aspects of affected systems. Remote attackers can leverage this vulnerability to induce denial of service conditions that may result in complete service interruption, forcing system administrators to restart HAProxy processes and potentially causing cascading failures in dependent services. Beyond service disruption, the buffer overflow creates opportunities for arbitrary code execution, potentially allowing attackers to gain unauthorized access to the system, escalate privileges, or establish persistent backdoors. The vulnerability affects organizations that rely on HAProxy for critical load balancing operations, where even brief service interruptions can result in significant financial losses and reputational damage. Network administrators face the challenge of identifying and mitigating this vulnerability across multiple systems while maintaining service availability during remediation efforts.
Organizations should implement immediate mitigations including upgrading to HAProxy version 1.4.21 or later, which contains the necessary patches to address the buffer overflow conditions. The upgrade process should be carefully planned to minimize service disruption while ensuring all affected systems receive the security updates. Additionally, administrators should review and adjust global.tune.bufsize configurations to avoid settings that exceed recommended limits, particularly when header rewriting functionality is enabled. Network segmentation and access controls should be strengthened to limit potential attack vectors, while intrusion detection systems should be configured to monitor for suspicious HTTP header patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-121 and CWE-122 categories related to stack and heap-based buffer overflows, and its exploitation techniques correspond to ATT&CK tactics including privilege escalation and defense evasion through service disruption. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable software and ensure comprehensive protection across the organization's infrastructure.