CVE-2008-5045 in FTP Now
Summary
by MITRE
Heap-based buffer overflow in Network-Client FTP Now 2.6, and possibly other versions, allows remote FTP servers to cause a denial of service (crash) via a 200 server response that is exactly 1024 characters long.
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Analysis
by VulDB Data Team • 11/10/2024
The vulnerability identified as CVE-2008-5045 represents a critical heap-based buffer overflow flaw in Network-Client FTP Now version 2.6 and potentially other affected implementations. This security defect arises from improper input validation within the FTP client's response handling mechanism, specifically when processing server responses that are exactly 1024 characters in length. The vulnerability operates by exploiting the client's failure to properly bounds-check incoming data before copying it into allocated heap memory buffers, creating a condition where maliciously crafted responses can overwrite adjacent memory regions.
The technical exploitation of this vulnerability occurs through a carefully constructed 200 server response that precisely matches the buffer size threshold of 1024 characters. When the FTP client processes this response, the insufficient boundary checking allows the data to overflow into adjacent heap memory locations, potentially corrupting heap metadata or overwriting critical program structures. This heap corruption typically results in immediate program termination or system crash, manifesting as a denial of service condition that prevents legitimate users from accessing the FTP service. The vulnerability's classification as heap-based indicates that the overflow affects dynamically allocated memory regions managed by the program's heap allocator rather than stack-based buffers.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on Network-Client FTP Now for file transfer operations. The remote exploitation capability means that malicious actors can trigger the denial of service condition from any location without requiring local access or authentication credentials. This makes the vulnerability particularly dangerous in environments where FTP services are exposed to untrusted networks or where automated scanning tools might exploit the flaw. The specific 1024-character threshold suggests that attackers can craft precise payloads that maximize the exploitation effectiveness while minimizing detectability, as the response size is within normal FTP protocol parameters.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows data to overwrite heap memory regions. This flaw also relates to ATT&CK technique T1499.004, which covers network denial of service attacks through exploitation of software vulnerabilities in network services. Organizations utilizing this FTP client software face potential operational disruptions that could affect business continuity, particularly in scenarios where file transfer operations are critical to business processes. The vulnerability demonstrates how seemingly benign protocol responses can be weaponized to create system instability.
Mitigation strategies for CVE-2008-5045 should prioritize immediate software updates to patched versions of Network-Client FTP Now or complete replacement with more secure FTP client implementations. Network administrators should implement defensive measures such as firewall rules that limit FTP server access to trusted networks, and consider deploying intrusion detection systems that can identify suspicious FTP response patterns. Additionally, organizations should establish monitoring procedures to detect potential exploitation attempts and maintain comprehensive backup and recovery procedures to minimize disruption from denial of service incidents. The vulnerability underscores the importance of regular security assessments and vulnerability management programs to identify and remediate similar heap-based buffer overflow conditions in network client software implementations.