CVE-2003-0625 in xfstt
Summary
by MITRE
Off-by-one error in certain versions of xfstt allows remote attackers to read potentially sensitive memory via a malformed client request in the connection handshake, which leaks the memory in the server s response.
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Analysis
by VulDB Data Team • 10/14/2024
The vulnerability identified as CVE-2003-0625 represents a critical off-by-one error within the xfstt service implementation that affects certain versions of the X Font Server Transport protocol. This flaw exists in the handling of client connection handshake requests where the server fails to properly validate the length of incoming data, creating a condition where a malformed request can trigger unauthorized memory access patterns. The issue stems from insufficient boundary checking during the parsing of connection handshake messages, allowing attackers to manipulate the data flow in ways that cause the server to return unintended memory contents in its response.
The technical implementation of this vulnerability manifests through the improper handling of buffer boundaries during the connection establishment phase of the xfstt protocol. When a client sends a specially crafted malformed request, the server's parsing routine processes the data incorrectly due to the off-by-one error, which typically occurs when the boundary conditions for array or buffer access are not properly validated. This error condition results in the server reading one additional byte beyond the intended buffer limits, causing it to include adjacent memory contents in its response packet. The memory leakage can potentially contain sensitive information such as authentication tokens, session data, or other confidential server state information that should remain protected from external access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides remote attackers with a mechanism to gather intelligence about the server's memory layout and potentially extract credentials or other sensitive data. Attackers can leverage this vulnerability to perform reconnaissance activities against systems running vulnerable xfstt implementations, making it particularly dangerous in environments where font servers are accessible from untrusted networks. The remote nature of the attack means that adversaries do not require local access or authentication to exploit the flaw, making it a significant threat vector for network-based attacks. This vulnerability directly relates to CWE-121, which addresses buffer overflow conditions in heap-based memory structures, and aligns with ATT&CK technique T1083 for discovering system information through network reconnaissance activities.
Mitigation strategies for CVE-2003-0625 require immediate patching of affected xfstt implementations with proper boundary validation and input sanitization measures. System administrators should ensure that all instances of the xfstt service are updated to versions that properly validate the length of incoming connection handshake data and implement robust buffer overflow protection mechanisms. Network segmentation and firewall rules should be implemented to restrict access to font server ports from untrusted networks, reducing the attack surface for remote exploitation. Additionally, monitoring systems should be configured to detect unusual patterns in connection handshake requests that may indicate exploitation attempts, as the memory leakage typically occurs during the initial connection phase when the server responds to malformed requests. The vulnerability demonstrates the importance of proper input validation in network services and highlights the need for comprehensive security testing of protocol implementations to prevent similar off-by-one errors in other components.