CVE-2016-4051 in Squid
Summary
by MITRE
Buffer overflow in cachemgr.cgi in Squid 2.x, 3.x before 3.5.17, and 4.x before 4.0.9 might allow remote attackers to cause a denial of service or execute arbitrary code by seeding manager reports with crafted data.
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Analysis
by VulDB Data Team • 10/21/2018
The vulnerability identified as CVE-2016-4051 represents a critical buffer overflow flaw within the cachemgr.cgi component of the Squid web proxy server software. This issue affects multiple versions spanning Squid 2.x through 3.x versions prior to 3.5.17 and 4.x versions before 4.0.9, making it a widespread concern across several major releases of the proxy software. The vulnerability resides in how the system processes manager reports, specifically when handling crafted input data that is seeded into the cache management interface.
The technical exploitation of this buffer overflow occurs through the manipulation of input data within the cachemgr.cgi script, which serves as the administrative interface for Squid cache management. When remote attackers provide specially crafted data to the manager reports functionality, the application fails to properly validate or limit the size of input parameters, leading to memory corruption that can result in either denial of service conditions or arbitrary code execution on the affected system. This type of vulnerability falls under the CWE-121 buffer overflow category, specifically categorized as a stack-based buffer overflow where insufficient bounds checking allows attackers to overwrite adjacent memory locations.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with potential paths to gain unauthorized access to systems running vulnerable Squid versions. The ability to execute arbitrary code remotely means that compromised systems could be used as launch points for further attacks within network infrastructure, making this a significant concern for organizations relying on Squid as a core proxy service. The vulnerability's remote exploitability without authentication requirements makes it particularly dangerous in environments where proxy servers are exposed to untrusted networks or internet-facing services.
Organizations should prioritize immediate patching of all affected Squid versions to address this vulnerability, as the attack surface includes any system running vulnerable software. The mitigation strategy should encompass not only updating to patched versions but also implementing network segmentation to limit exposure of proxy services to untrusted networks. Security monitoring should be enhanced to detect unusual patterns in cache manager report processing, and input validation should be strengthened throughout the application to prevent similar issues in the future. The vulnerability demonstrates the importance of robust input validation and memory safety practices in network infrastructure software, aligning with ATT&CK techniques related to privilege escalation and remote code execution through software vulnerabilities.