CVE-2008-1620 in ThinClientServer
Summary
by MITRE
Directory traversal vulnerability in 2X TFTP service (TFTPd.exe) 3.2.0.0 and earlier in 2X ThinClientServer 5.0_sp1-r3497 and earlier allows remote attackers to read or overwrite arbitrary files via a ... (dot dot dot) in the filename.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/22/2018
The vulnerability identified as CVE-2008-1620 represents a critical directory traversal flaw within the 2X TFTP service component known as TFTPd.exe version 3.2.0.0 and earlier. This vulnerability affects the 2X ThinClientServer 5.0_sp1-r3497 and earlier versions, creating a significant security risk that could be exploited by remote attackers to gain unauthorized access to system resources. The flaw stems from insufficient input validation within the TFTP service implementation, specifically when processing filename parameters that contain directory traversal sequences.
The technical exploitation of this vulnerability occurs through the use of dot dot dot sequences in filename parameters, which allows attackers to navigate beyond the intended directory boundaries. When the TFTP service processes these malformed filenames, it fails to properly sanitize or validate the input, enabling attackers to specify paths that reference files outside the designated TFTP root directory. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability essentially allows an attacker to bypass normal access controls and potentially read sensitive system files, overwrite critical files, or execute arbitrary code depending on the permissions of the TFTP service account.
From an operational perspective, this vulnerability poses severe risks to organizations utilizing 2X ThinClientServer environments, particularly in enterprise settings where TFTP services are commonly used for network booting, firmware updates, and remote system management. Remote attackers can leverage this flaw to access configuration files, system binaries, or other sensitive data stored on the server, potentially leading to complete system compromise. The impact extends beyond simple data theft as attackers could overwrite system files, corrupt the TFTP service, or establish persistent access points. According to ATT&CK framework, this vulnerability aligns with T1059 (Command and Scripting Interpreter) and T1071 (Application Layer Protocol) techniques, as attackers may use the TFTP service as a foothold for further exploitation while leveraging legitimate network protocols.
The mitigation strategies for this vulnerability primarily involve immediate patching of the affected 2X ThinClientServer components to versions that properly implement input validation and sanitize all filename parameters before processing. Organizations should also implement network segmentation to limit access to TFTP services, restrict TFTP service access to trusted networks only, and monitor for suspicious TFTP traffic patterns. Additionally, implementing proper file system permissions and privilege separation for the TFTP service account can help minimize the potential impact if exploitation occurs. Security administrators should also consider disabling TFTP services when not actively needed and implement network-based intrusion detection systems to monitor for directory traversal attempts in TFTP traffic, as this vulnerability represents a well-known attack pattern that can be easily automated by threat actors.