CVE-2015-0928 in libhtp
Summary
by MITRE
libhtp 0.5.15 allows remote attackers to cause a denial of service (NULL pointer dereference).
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2015-0928 affects libhtp version 0.5.15, a library designed for HTTP protocol parsing and processing. This flaw represents a critical denial of service vulnerability that can be exploited by remote attackers to disrupt service availability. The issue stems from improper handling of malformed HTTP requests within the library's parsing logic, specifically manifesting as a NULL pointer dereference condition that leads to application termination.
The technical implementation of this vulnerability occurs when libhtp processes specially crafted HTTP traffic that contains malformed headers or request structures. During the parsing phase, the library attempts to access a NULL pointer reference when encountering certain invalid HTTP constructs, causing the application to crash and terminate unexpectedly. This behavior aligns with CWE-476, which describes NULL pointer dereference vulnerabilities that occur when a program attempts to access memory through a pointer that has not been properly initialized or has been set to NULL. The vulnerability is particularly concerning because it can be triggered through standard HTTP traffic without requiring authentication or specialized privileges, making it highly exploitable in networked environments.
From an operational perspective, this vulnerability poses significant risks to systems that rely on libhtp for HTTP processing, including web application firewalls, intrusion detection systems, and proxy servers. Attackers can leverage this flaw to perform sustained denial of service attacks against targeted systems by sending malicious HTTP requests that trigger the NULL pointer dereference. The impact extends beyond simple service disruption, as the vulnerability can be used in conjunction with other attack vectors to create more sophisticated exploitation scenarios. The ATT&CK framework categorizes this type of vulnerability under T1499.004, which covers network denial of service attacks, and T1595.001, which involves network scanning and reconnaissance activities that may precede exploitation.
Mitigation strategies for CVE-2015-0928 involve immediate patching of affected systems to upgrade to libhtp version 0.5.16 or later, which contains the necessary fixes for the NULL pointer dereference issue. Network administrators should implement rate limiting and traffic filtering mechanisms to detect and block suspicious HTTP patterns that may indicate exploitation attempts. Additionally, deploying intrusion prevention systems with signature updates that can identify and block malicious HTTP traffic is recommended. Organizations should also conduct thorough vulnerability assessments to identify all systems that utilize libhtp and ensure comprehensive patch management procedures are in place. The remediation process should include testing patches in controlled environments before deployment to prevent potential compatibility issues with existing applications that depend on the library's functionality.