CVE-2012-1180 in nginx
Summary
by MITRE
Use-after-free vulnerability in nginx before 1.0.14 and 1.1.x before 1.1.17 allows remote HTTP servers to obtain sensitive information from process memory via a crafted backend response, in conjunction with a client request.
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Analysis
by VulDB Data Team • 03/22/2021
The CVE-2012-1180 vulnerability represents a critical use-after-free flaw in the nginx web server software that existed in versions prior to 1.0.14 and 1.1.x versions before 1.1.17. This vulnerability specifically targets the interaction between nginx's proxy module and backend server responses, creating a scenario where remote HTTP servers can potentially extract sensitive information from process memory through carefully crafted responses. The flaw exploits a fundamental memory management issue where nginx continues to reference memory locations that have already been freed, creating opportunities for information disclosure attacks.
The technical implementation of this vulnerability occurs within nginx's handling of backend responses when acting as a proxy server. When nginx receives a response from a backend server, it processes this data and may free certain memory structures associated with that response. However, a race condition or improper state management allows a malicious backend server to manipulate the timing or content of responses in such a way that when nginx attempts to access previously freed memory locations, it inadvertently exposes sensitive data from the process memory space. This type of vulnerability falls under the CWE-416 category of use-after-free conditions, which are classified as severe memory safety issues that can lead to information disclosure, remote code execution, or system compromise.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a significant threat vector for attackers seeking to harvest sensitive data from nginx processes. Attackers can leverage this vulnerability by controlling a backend server or intercepting network traffic to a backend server, crafting malicious responses that trigger the use-after-free condition. The sensitive information that may be exposed includes session tokens, user credentials, database connection details, or other confidential data stored in memory. This vulnerability directly impacts nginx deployments in production environments where the web server acts as a reverse proxy or load balancer, making it particularly dangerous for organizations relying on nginx for critical web services and application delivery.
Mitigation strategies for CVE-2012-1180 primarily focus on immediate version upgrades to patched nginx releases, specifically updating to versions 1.0.14 or 1.1.17 and later. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious backend servers, while monitoring for unusual backend response patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper memory management practices and thorough testing of proxy and caching mechanisms. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1071.004 for application layer protocol manipulation and T1005 for data from local system, highlighting the need for comprehensive security controls that address both network and application-level threats. Organizations should also consider implementing intrusion detection systems that can identify suspicious backend response patterns and maintain regular vulnerability assessment programs to identify similar memory safety issues in other software components.