CVE-2012-5332 in Reverse Proxy
Summary
by MITRE
at32 Reverse Proxy 1.060.310 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a long string in an HTTP header field, as demonstrated using the If-Unmodified-Since field.
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Analysis
by VulDB Data Team • 02/06/2018
The vulnerability identified as CVE-2012-5332 affects the at32 Reverse Proxy version 1.060.310, representing a critical denial of service weakness that can be exploited remotely by malicious actors. This issue stems from improper input validation mechanisms within the proxy server's handling of HTTP header fields, specifically targeting the If-Unmodified-Since header field. The flaw manifests when the proxy receives a specially crafted HTTP request containing an excessively long string within this header, leading to a NULL pointer dereference condition that ultimately results in application crash and complete service disruption.
The technical implementation of this vulnerability demonstrates a classic buffer overflow scenario where the proxy server fails to properly validate the length and content of incoming HTTP header values before processing them. When the If-Unmodified-Since header contains an abnormally long string, the reverse proxy's parsing logic attempts to access memory locations that have not been properly initialized or allocated, resulting in a NULL pointer dereference. This type of error falls under the CWE-476 category of NULL Pointer Dereference, which is a well-documented weakness in software security practices. The vulnerability operates at the application layer of the network stack, making it particularly dangerous as it can be triggered through standard HTTP traffic without requiring any special privileges or authentication.
The operational impact of this vulnerability extends beyond simple service interruption, as it can be leveraged by attackers to perform sustained denial of service attacks against targeted systems. Remote attackers can exploit this weakness by crafting HTTP requests with malformed If-Unmodified-Since headers containing strings that exceed the proxy's expected buffer sizes, causing the application to crash repeatedly. This creates a cascading effect where legitimate users experience service degradation or complete unavailability of the proxy services. The attack vector is particularly concerning because it can be executed through standard web browsing or automated tools, making it accessible to threat actors with minimal technical expertise. The vulnerability affects the availability aspect of the CIA triad, specifically targeting the service's ability to remain operational and responsive to legitimate requests.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and bounds checking mechanisms within the proxy server's HTTP header processing routines. Organizations should immediately apply the vendor-supplied patches or updates that address this specific NULL pointer dereference issue in at32 Reverse Proxy version 1.060.310. Additionally, network administrators should implement rate limiting and connection monitoring to detect and block suspicious traffic patterns that may indicate exploitation attempts. The implementation of web application firewalls and intrusion detection systems can provide additional layers of protection by monitoring for malformed HTTP headers and abnormal request patterns. Security teams should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems. From an ATT&CK framework perspective, this vulnerability aligns with the T1499.004 technique of Network Denial of Service, which involves the exploitation of software vulnerabilities to disrupt network services. The remediation approach should include comprehensive testing of patched systems to verify that the vulnerability has been properly addressed and that normal service operations can resume without risk of re-exploitation.