CVE-2008-7016 in tnftpd
Summary
by MITRE
tnftpd before 20080929 splits large command strings into multiple commands, which allows remote attackers to conduct cross-site request forgery (CSRF) attacks via unknown vectors, probably involving a crafted ftp:// link to a tnftpd server.
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Analysis
by VulDB Data Team • 03/12/2017
The vulnerability described in CVE-2008-7016 affects tnftpd versions prior to 20080929 and represents a cross-site request forgery weakness that emerges from how the FTP daemon handles large command strings. This issue stems from the software's implementation of command parsing where lengthy input sequences are automatically segmented into multiple discrete commands, creating an unexpected behavior that can be exploited by malicious actors. The flaw exists within the protocol handling layer of the ftp daemon, specifically in how it processes and interprets command line arguments that exceed certain size thresholds, making it susceptible to manipulation through crafted input sequences.
The technical mechanism behind this vulnerability involves tnftpd's command string processing algorithm which splits commands exceeding predefined length limits into smaller segments for processing. When a remote attacker crafts a specially formatted ftp:// URL containing extended command sequences, the server's automatic command splitting functionality can be manipulated to execute unintended operations. This behavior creates a potential attack surface where malicious links can trigger unauthorized actions on behalf of users who interact with the compromised ftp server. The vulnerability's exploitation requires careful construction of input data that leverages the automatic command segmentation feature to bypass normal security checks and authentication mechanisms.
The operational impact of CVE-2008-7016 extends beyond simple CSRF attacks to potentially enable more sophisticated exploitation patterns within ftp server environments. Attackers can craft malicious ftp:// links that, when accessed by unsuspecting users, trigger unauthorized file operations or command executions on the target server. This vulnerability particularly affects web browsers and applications that automatically process ftp:// URLs without proper validation, making it a significant concern for organizations relying on ftp services for file transfers. The attack vector operates through web-based interfaces or applications that may automatically initiate ftp connections, creating opportunities for unauthorized command execution and potential data compromise.
Security mitigations for this vulnerability primarily focus on updating to the patched version of tnftpd released after 20080929, which addresses the command string splitting behavior that enables the CSRF attack. System administrators should implement strict input validation measures to prevent oversized command sequences from being processed, and consider configuring the ftp daemon to reject or properly sanitize extended command arguments. Network-level protections can include implementing firewall rules that restrict ftp service access and monitoring for unusual command patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-346, which addresses improper validation of data integrity, and relates to ATT&CK technique T1566.001 for spearphishing attachments, as the attack often involves crafting malicious links that appear legitimate to end users. Organizations should also implement comprehensive logging and monitoring to detect anomalous ftp command sequences that could indicate exploitation attempts.