CVE-2006-6241 in Telnet-FTP Server
Summary
by MITRE
Sorin Chitu Telnet-FTP Server 1.0 allows remote authenticated users to cause a denial of service (crash) via consecutive RETR commands. NOTE: The provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 09/30/2017
The vulnerability identified as CVE-2006-6241 affects the Sorin Chitu Telnet-FTP Server version 1.0, representing a significant security flaw that enables remote authenticated attackers to induce a denial of service condition through carefully crafted RETR commands. This vulnerability resides within the server's handling of file retrieval operations, specifically when multiple RETR commands are issued consecutively, leading to a system crash that disrupts legitimate service availability.
The technical nature of this flaw demonstrates a classic buffer over-read or improper state management issue within the FTP server implementation. When authenticated users submit consecutive RETR commands, the server fails to properly validate or handle the sequence of operations, resulting in a condition that causes the application to terminate unexpectedly. This type of vulnerability falls under the category of improper input validation and resource management issues that are commonly classified under CWE-129 and CWE-399. The vulnerability represents a failure in the server's ability to maintain stable operation under concurrent or sequential command processing, indicating a lack of proper error handling and state machine implementation.
From an operational perspective, this vulnerability presents a substantial risk to organizations relying on the affected Telnet-FTP server implementation. The fact that remote authenticated users can trigger a crash means that legitimate users who have established valid connections can potentially disrupt service availability for all other users. The impact extends beyond simple service interruption as it can be exploited systematically to maintain persistent denial of service conditions, particularly in environments where the server handles multiple concurrent connections. This vulnerability can be leveraged as part of a broader attack strategy to degrade service availability, potentially masking other malicious activities or creating opportunities for further exploitation.
The attack vector for this vulnerability requires that an attacker already possesses valid authentication credentials, which limits the scope to authenticated users. However, this does not diminish the severity of the impact, as it can be combined with other vulnerabilities or used in conjunction with social engineering tactics to gain access. The vulnerability's classification aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a form of resource exhaustion or service disruption that can be difficult to detect and trace. Organizations should consider implementing monitoring for unusual command sequences or connection patterns that might indicate exploitation attempts.
Mitigation strategies for this vulnerability should include immediate software updates or patches provided by the vendor, if available, and implementation of access controls to limit the number of concurrent connections or command sequences that can be executed by authenticated users. Network segmentation and monitoring solutions should be deployed to detect and alert on unusual command patterns that could indicate exploitation attempts. Additionally, organizations should implement proper input validation and error handling mechanisms within their FTP server configurations to prevent similar issues from occurring in other services. The vulnerability highlights the importance of proper state management in network services and the necessity of robust error handling to prevent crashes from occurring during legitimate user operations.