CVE-2006-0223 in 123 Flash Chat Server
Summary
by MITRE
Directory traversal vulnerability in Shanghai TopCMM 123 Flash Chat Server Software 5.1 allows attackers to create or overwrite arbitrary files on the server via ".." (dot dot) sequences in the username field.
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Analysis
by VulDB Data Team • 08/04/2017
The CVE-2006-0223 vulnerability represents a critical directory traversal flaw in the Shanghai TopCMM 123 Flash Chat Server Software version 5.1, exposing servers to arbitrary file manipulation attacks. This vulnerability specifically targets the username field processing mechanism where the software fails to properly validate or sanitize input containing directory traversal sequences. The flaw enables malicious actors to exploit the server's file system by crafting usernames that contain ".." (dot dot) sequences, which are standard path traversal indicators used to navigate up directory levels in file systems. When the server processes these malformed usernames, it does not adequately restrict the path resolution, allowing attackers to specify arbitrary file paths outside the intended directory structure.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the authentication and user management components of the chat server software. The software's username handling routine appears to directly incorporate user-supplied input into file system operations without proper path normalization or security checks. This weakness creates an opportunity for attackers to manipulate the server's file system operations by injecting traversal sequences that bypass normal access controls. The vulnerability is particularly dangerous because it allows not only file reading but also file creation and overwriting operations, potentially enabling complete server compromise through malicious file deployment or data corruption.
Operationally, this vulnerability presents severe implications for organizations using the affected software, as it provides attackers with direct access to the underlying file system. An attacker could leverage this flaw to overwrite critical system files, inject malicious code into the server, or create backdoor access points. The impact extends beyond simple file manipulation to include potential privilege escalation and persistent access to the compromised server. The vulnerability's exploitability is relatively straightforward, requiring only a crafted username containing traversal sequences, making it attractive to attackers who may not possess advanced technical skills. Organizations running this software face significant risk of unauthorized access, data breaches, and potential complete system compromise, especially when the server operates with elevated privileges.
Mitigation strategies for this vulnerability should focus on immediate input validation and sanitization within the affected software components. System administrators should implement proper path validation routines that reject or normalize directory traversal sequences in user input fields, particularly those used for authentication and account management. The solution requires implementing strict input filtering that removes or encodes potentially dangerous characters including "..", "/", "\", and other path traversal indicators. Organizations should also consider applying the vendor's official patches or upgrading to newer versions of the software that address this specific vulnerability. From a defensive perspective, implementing network segmentation and access controls can limit the impact of potential exploitation. The vulnerability aligns with CWE-22 Directory Traversal and falls under ATT&CK technique T1059 Command and Scripting Interpreter, as it enables attackers to execute arbitrary commands through file system manipulation. Additionally, this weakness demonstrates the importance of secure input handling practices and proper sandboxing of user-supplied data to prevent unauthorized system access.