CVE-2018-10243 in libhtp
Summary
by MITRE
htp_parse_authorization_digest in htp_parsers.c in LibHTP 0.5.26 allows remote attackers to cause a heap-based buffer over-read via an authorization digest header.
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Analysis
by VulDB Data Team • 08/25/2023
The vulnerability identified as CVE-2018-10243 resides within the LibHTP library version 0.5.26, specifically in the htp_parse_authorization_digest function located in htp_parsers.c. This flaw represents a heap-based buffer over-read that can be exploited by remote attackers to potentially execute arbitrary code or cause service disruption. The issue occurs when processing authorization digest headers, which are commonly used in HTTP authentication mechanisms to provide a more secure alternative to basic authentication. The vulnerability demonstrates a classic buffer management error where the parser fails to properly validate the boundaries of memory allocations when handling digest authentication headers.
The technical implementation of this vulnerability stems from improper input validation within the authorization digest parsing routine. When the htp_parse_authorization_digest function processes incoming authorization headers, it does not adequately check the length of the digest parameters against the allocated buffer space. This oversight allows an attacker to craft malicious authorization headers with oversized parameter values that exceed the intended buffer boundaries. The heap-based nature of the over-read means that the vulnerability can be exploited to read memory contents beyond the allocated heap region, potentially exposing sensitive data or allowing for more sophisticated attack vectors. The flaw aligns with CWE-125, which describes out-of-bounds read vulnerabilities that occur when software reads data past the end of a buffer, and represents a common class of memory safety issues in C-based applications.
The operational impact of CVE-2018-10243 extends beyond simple denial of service scenarios, as the heap over-read could potentially expose confidential information stored in adjacent memory locations. Attackers could leverage this vulnerability to extract session tokens, cryptographic keys, or other sensitive data that might be stored in memory adjacent to the affected buffer. The remote exploitability of this vulnerability means that attackers do not require local system access, making it particularly dangerous in web server environments where LibHTP is commonly deployed. When exploited successfully, the vulnerability could lead to complete system compromise, especially if the affected application processes sensitive user data or authentication information. The attack vector involves sending specially crafted authorization digest headers to a vulnerable service, making it difficult to distinguish from legitimate traffic and potentially enabling stealthy exploitation.
Mitigation strategies for CVE-2018-10243 should prioritize immediate patching of affected LibHTP installations to version 0.5.27 or later, which contains the necessary fixes for the buffer over-read issue. Organizations should also implement network-based detection measures such as intrusion detection systems that can identify malformed authorization headers attempting to exploit this vulnerability. Additionally, the deployment of web application firewalls with signature-based detection capabilities can help prevent exploitation attempts. From a defensive perspective, input validation should be enhanced at multiple layers of the application stack, including implementing strict bounds checking for all header parsing operations. The vulnerability highlights the importance of memory safety practices and proper buffer management in security-critical applications, aligning with ATT&CK technique T1059.007 for execution through web shells and T1190 for exploitation of remote services. Organizations should also consider implementing runtime protection mechanisms such as address space layout randomization and stack canaries to further reduce the exploitability of similar buffer overflow vulnerabilities in their systems.