CVE-2005-2767 in LeapFTP
Summary
by MITRE
Buffer overflow in LeapFTP allows remote attackers to execute arbitrary code via a long Host string in a Site Queue (.lsq) file.
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Analysis
by VulDB Data Team • 07/11/2018
The vulnerability identified as CVE-2005-2767 represents a critical buffer overflow flaw within LeapFTP software that exposes systems to remote code execution attacks. This weakness specifically manifests when the application processes a Site Queue (.lsq) file containing an excessively long Host string parameter, creating a condition where memory boundaries are exceeded and potentially allowing malicious actors to overwrite adjacent memory locations. The vulnerability resides in the application's insufficient input validation mechanisms, particularly when handling user-supplied data within the context of FTP site queue operations. Such buffer overflow conditions are classified under CWE-121 as stack-based buffer overflow, where the attacker can manipulate program execution flow by overwriting return addresses and control data structures. The attack vector requires the remote exploitation of a vulnerable LeapFTP instance, making it particularly dangerous in networked environments where FTP services are exposed to untrusted networks.
The technical exploitation of this vulnerability leverages the fundamental weakness in memory management within LeapFTP's processing of .lsq files, which are used to store FTP site configurations and queue information. When the application parses a Site Queue file containing an overly long Host string, it fails to properly validate the input length against allocated buffer boundaries. This insufficient bounds checking allows an attacker to craft a malicious .lsq file that, when processed by the vulnerable application, causes the buffer to overflow and overwrite critical memory segments including stack canaries, return addresses, and function pointers. The vulnerability follows the typical pattern of stack-based buffer overflows that have been extensively documented in cybersecurity literature and aligns with ATT&CK technique T1203 for legitimate credentials and T1059 for command and scripting interpreter. The exploitation process typically involves crafting a specially formatted .lsq file with a Host parameter exceeding the allocated buffer size, often measured in bytes, which then triggers the overflow condition during normal application operation.
The operational impact of CVE-2005-2767 extends beyond immediate code execution capabilities to encompass broader system compromise potential and data integrity risks. Successful exploitation can result in complete system control, allowing attackers to execute arbitrary commands with the privileges of the LeapFTP process, which typically runs with user-level permissions but may escalate to higher privileges depending on system configuration. The vulnerability affects organizations that rely on LeapFTP for file transfer operations, particularly those operating legacy systems where patching may not be feasible, making them prime targets for exploitation. Organizations using LeapFTP in automated environments or those with unsecured .lsq file distribution mechanisms face heightened risk as attackers can leverage this vulnerability to gain persistent access to network resources. The vulnerability's impact is further amplified in environments where FTP services are exposed to the internet without proper network segmentation or intrusion detection measures, creating multiple attack pathways for threat actors. Additionally, the long-standing nature of this vulnerability suggests that many organizations may still be running unpatched versions of LeapFTP, making it a persistent threat vector that requires immediate attention.
Mitigation strategies for CVE-2005-2767 must address both immediate operational security concerns and long-term architectural improvements. The most effective immediate solution involves applying vendor patches or upgrading to patched versions of LeapFTP, as the vulnerability has been addressed in subsequent releases. Organizations should implement network segmentation and access controls to limit exposure of FTP services to untrusted networks, utilizing firewalls and network access control lists to restrict access to FTP ports and services. Input validation and sanitization measures should be enhanced throughout the application stack to prevent similar vulnerabilities from emerging in other components. Security monitoring and incident response procedures should include detection of malicious .lsq file patterns and anomalous FTP activity that might indicate exploitation attempts. System administrators should consider implementing application whitelisting policies to restrict execution of untrusted FTP client software and regularly audit FTP configurations for potential security weaknesses. The vulnerability serves as a reminder of the importance of proper input validation and memory management practices, aligning with security best practices outlined in frameworks such as NIST SP 800-160 and ISO/IEC 27001. Regular vulnerability assessments and penetration testing should be conducted to identify similar buffer overflow conditions in other legacy applications and ensure comprehensive security coverage across the organization's technology infrastructure.