CVE-2008-3705 in EchoVNC
Summary
by MITRE
Stack-based buffer overflow in the CLogger::WriteFormated function in echoware/Logger.cpp in EchoVNC Linux before 1.1.2 allows remote echoServers to execute arbitrary code via a large (1) group or (2) user list, aka a "very crowded echoServer" attack. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 10/05/2018
The vulnerability identified as CVE-2008-3705 represents a critical stack-based buffer overflow flaw within the EchoVNC Linux software version 1.1.1 and earlier. This security weakness exists in the CLogger::WriteFormated function located in the echoware/Logger.cpp source file, creating a significant exposure that remote attackers can exploit to execute arbitrary code on affected systems. The vulnerability specifically targets the handling of group and user list data structures within the echoServer functionality, making it particularly dangerous in networked environments where multiple users interact with the system.
The technical implementation of this buffer overflow stems from insufficient input validation and bounds checking within the logging subsystem. When the CLogger::WriteFormated function processes large group or user list inputs, it fails to properly validate the size of incoming data against the allocated stack buffer space. This allows an attacker to overflow the buffer and overwrite adjacent memory locations, including return addresses and function pointers. The attack vector specifically leverages the "very crowded echoServer" scenario where maliciously crafted large user or group lists are submitted to the server, triggering the vulnerable code path and enabling remote code execution. This flaw aligns with CWE-121 Stack-based Buffer Overflow, which is categorized under the broader category of CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the affected EchoVNC server. An attacker could potentially gain unauthorized access to the system, escalate privileges, install persistent backdoors, or use the compromised server as a launch point for further attacks within the network infrastructure. The vulnerability is particularly concerning because it allows remote exploitation without requiring authentication, making it an attractive target for automated attacks and making the impact more severe in environments where EchoVNC servers are exposed to untrusted networks. The specific nature of the attack requires only the submission of oversized user or group lists, which can be easily accomplished through network-based input manipulation, aligning with ATT&CK technique T1059.007 Command and Scripting Interpreter: Python and T1203 Exploitation for Client Execution patterns.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected systems to version 1.1.2 or later, which contains the necessary fixes to prevent buffer overflow conditions. System administrators should implement input validation controls that enforce strict limits on user and group list sizes, particularly in the logging components of the software. Network segmentation and access controls should be enforced to limit exposure of EchoVNC servers to trusted networks only, reducing the attack surface available to potential adversaries. Additionally, monitoring and logging mechanisms should be enhanced to detect anomalous user or group list submissions that might indicate attempted exploitation of this vulnerability, providing early warning capabilities for security teams to respond to potential attacks. The vulnerability demonstrates the importance of proper input validation and memory management practices in networked applications, particularly those handling user-provided data in server environments.