CVE-2003-0963 in lftp
Summary
by MITRE
Buffer overflows in (1) try_netscape_proxy and (2) try_squid_eplf for lftp 2.6.9 and earlier allow remote HTTP servers to execute arbitrary code via long directory names that are processed by the ls or rels commands.
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Analysis
by VulDB Data Team • 07/20/2025
The vulnerability described in CVE-2003-0963 represents a critical buffer overflow flaw affecting lftp version 2.6.9 and earlier. This security issue manifests in two distinct code paths within the lftp application, specifically in the try_netscape_proxy and try_squid_eplf functions. The vulnerability arises when lftp processes directory listings from remote HTTP servers, particularly during the execution of ls or rels commands. These functions fail to properly validate the length of directory names received from HTTP servers, creating opportunities for attackers to craft malicious directory listings that exceed buffer boundaries. The flaw directly relates to CWE-121, which categorizes buffer overflow conditions where insufficient boundary checking allows attackers to overwrite adjacent memory locations.
The technical exploitation of this vulnerability requires a remote HTTP server to send directory listings containing excessively long directory names that trigger buffer overflow conditions in the affected lftp functions. When lftp processes these malformed directory names, the insufficient input validation causes memory corruption that can be leveraged to execute arbitrary code on the victim system. The attack vector is particularly concerning because it operates over HTTP connections, making it accessible to remote attackers without requiring local system access. The vulnerability demonstrates characteristics consistent with CWE-787, which describes out-of-bounds writes that occur when a program writes data past the end of a buffer, potentially corrupting adjacent memory regions.
The operational impact of this vulnerability extends beyond simple code execution, as it can lead to complete system compromise when exploited successfully. An attacker who controls a remote HTTP server can manipulate directory listings to inject malicious code into the lftp process memory space, potentially gaining unauthorized access to the system. This represents a significant threat to users who rely on lftp for file transfers and directory browsing operations, particularly in environments where the application may connect to untrusted HTTP servers. The vulnerability affects the core functionality of lftp's proxy handling mechanisms, making it particularly dangerous for users who frequently work with HTTP proxies and web-based file systems. The exploitation process aligns with ATT&CK technique T1059.007, which describes the use of command and scripting interpreters, as successful exploitation would likely involve injecting and executing malicious code within the target system's memory space.
Mitigation strategies for this vulnerability require immediate patching of lftp installations to versions that address the buffer overflow conditions in both try_netscape_proxy and try_squid_eplf functions. System administrators should implement network-level controls to restrict access to potentially malicious HTTP servers and consider deploying network monitoring solutions to detect unusual directory listing patterns. The fix should include proper input validation and bounds checking for directory name lengths, ensuring that all buffer operations are protected against overflow conditions. Additionally, users should be educated about the risks of connecting to untrusted HTTP servers and the importance of keeping their lftp installations updated. Organizations should consider implementing application whitelisting policies to prevent execution of vulnerable lftp versions, while also establishing regular vulnerability assessment procedures to identify similar buffer overflow conditions in other network utilities and applications.