CVE-2018-12684 in CivetWeb
Summary
by MITRE
Out-of-bounds Read in the send_ssi_file function in civetweb.c in CivetWeb through 1.10 allows attackers to cause a Denial of Service or Information Disclosure via a crafted SSI file.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability CVE-2018-12684 represents a critical out-of-bounds read flaw within the CivetWeb web server implementation that affects versions through 1.10. This issue resides in the send_ssi_file function located in the civetweb.c source file, demonstrating a classic buffer over-read condition that can be exploited through maliciously crafted Server-Side Includes files. The vulnerability specifically manifests when the web server processes SSI directives that contain malformed or oversized data structures, leading to memory access violations that can be leveraged by remote attackers to compromise system availability and confidentiality.
The technical exploitation of this vulnerability occurs when CivetWeb encounters SSI files containing specially crafted directives that trigger an out-of-bounds memory read operation during the processing of server-side includes. This flaw falls under the CWE-125 Out-of-bounds Read category, which represents one of the most common and dangerous classes of memory safety vulnerabilities in software systems. The vulnerability is particularly concerning because it allows attackers to either cause a denial of service through application crashes or potentially extract sensitive information from memory locations beyond the intended buffer boundaries. The SSI processing functionality in CivetWeb is designed to handle server-side includes for dynamic content generation, but the lack of proper bounds checking in the send_ssi_file function creates a path for attackers to manipulate memory access patterns.
From an operational perspective, this vulnerability presents significant risks to web server availability and data integrity within environments using CivetWeb as their HTTP server implementation. Attackers can leverage this flaw to cause unexpected application behavior including crashes, restarts, or memory corruption that leads to complete service disruption. Additionally, the information disclosure aspect of this vulnerability means that an attacker might be able to extract sensitive data from memory locations that should remain protected, potentially including session tokens, user credentials, or other confidential information. The impact is particularly severe in environments where CivetWeb serves as a primary web server for applications handling sensitive data, as the vulnerability could be exploited to compromise entire web applications.
The mitigation strategy for CVE-2018-12684 involves immediate upgrading to CivetWeb version 1.11 or later, where the out-of-bounds read issue has been resolved through proper bounds checking and input validation. Organizations should also implement defensive measures such as restricting SSI file access to trusted users only, disabling SSI processing when not required, and monitoring web server logs for suspicious SSI file access patterns. From a security framework perspective, this vulnerability aligns with ATT&CK technique T1190 - Exploit Public-Facing Application, and represents a clear example of how insufficient input validation can lead to both availability and confidentiality breaches. Network administrators should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability, as the attack surface remains relevant for systems that have not yet been patched or upgraded to secure versions of the software.