CVE-2001-0936 in Frox
Summary
by MITRE
Buffer overflow in Frox transparent FTP proxy 0.6.6 and earlier, with the local caching method selected, allows remote FTP servers to run arbitrary code via a long response to an MDTM request.
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Analysis
by VulDB Data Team • 06/04/2018
The vulnerability identified as CVE-2001-0936 represents a critical buffer overflow flaw within the Frox transparent FTP proxy software version 0.6.6 and earlier. This issue specifically manifests when the proxy utilizes the local caching method for handling FTP traffic, creating a pathway for remote attackers to execute arbitrary code on the affected system. The vulnerability stems from inadequate input validation within the proxy's response handling mechanism for MDTM (Modify Date and Time) requests, which are standard FTP commands used to retrieve file modification timestamps. When a remote FTP server responds to an MDTM request with an excessively long response string, the Frox proxy fails to properly bounds-check the data before copying it into a fixed-size buffer, resulting in memory corruption that can be exploited to gain control of the proxy process.
The technical exploitation of this vulnerability aligns with CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector involves a remote FTP server deliberately sending a malformed response to an MDTM request that exceeds the allocated buffer space, causing a stack-based buffer overflow that can be leveraged to overwrite return addresses and execute malicious code. This vulnerability operates under the MITRE ATT&CK framework within the T1059.007 technique category, specifically targeting remote code execution through network services. The operational impact extends beyond simple code execution, as successful exploitation can lead to complete system compromise, allowing attackers to establish persistent access, escalate privileges, or use the compromised proxy as a pivot point for further network reconnaissance and attacks.
The security implications of this vulnerability are particularly severe given that Frox serves as a transparent proxy, meaning it operates invisibly to both clients and servers, making detection of exploitation more difficult. Attackers can leverage this flaw to gain unauthorized access to the proxy server, potentially using it as a stepping stone for broader network infiltration. The local caching method exacerbates the risk by requiring the proxy to store and process FTP responses locally, increasing the attack surface for buffer overflow exploitation. Organizations using vulnerable versions of Frox should immediately implement mitigations including upgrading to patched versions, implementing network segmentation to isolate proxy services, and deploying intrusion detection systems to monitor for suspicious FTP traffic patterns. The vulnerability demonstrates the critical importance of proper input validation and bounds checking in network services, particularly those handling untrusted data from remote sources. Additionally, this case highlights the necessity of regular security assessments and patch management processes to prevent exploitation of known vulnerabilities in widely used network infrastructure components.