CVE-2008-0152 in SLNet RF Telnet Server
Summary
by MITRE
SLnet.exe in SeattleLab SLNet RF Telnet Server 4.1.1.3758 and earlier allows user-assisted remote attackers to cause a denial of service (crash) via unspecified telnet options, which triggers a NULL pointer dereference. NOTE: the crash is not user-assisted when the server is running in debug mode.
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Analysis
by VulDB Data Team • 11/03/2017
The vulnerability identified as CVE-2008-0152 affects the SLnet.exe component of SeattleLab SLNet RF Telnet Server version 4.1.1.3758 and earlier. This represents a critical security flaw that manifests as a denial of service condition, specifically causing the application to crash due to improper handling of telnet options. The vulnerability operates through a NULL pointer dereference mechanism, which occurs when the software attempts to access memory through a pointer that has not been properly initialized or has been set to NULL. This type of error falls under the CWE-476 category of NULL Pointer Dereference, a common weakness that can lead to application instability and system crashes.
The attack vector for this vulnerability involves sending specially crafted telnet options to the affected server, which triggers the malformed input processing error. The vulnerability is classified as user-assisted because an external attacker must first establish a connection to the telnet server and then send the malicious telnet options to cause the crash. However, the security implications become more severe when the server operates in debug mode, as the vulnerability transforms from user-assisted to automatic exploitation, meaning the crash can occur without any user interaction simply by connecting to the debug-enabled server. This characteristic significantly increases the attack surface and potential for automated exploitation.
From an operational standpoint, this vulnerability can severely impact the availability of the telnet server service, potentially disrupting legitimate user access and system operations. The denial of service condition can be particularly problematic for critical infrastructure applications where continuous availability is essential. The vulnerability affects the core functionality of the SLNet RF Telnet Server, which is commonly used for remote access and management of radio frequency equipment. When exploited, the crash can result in complete service interruption until the server is manually restarted, potentially causing operational delays and requiring system administrator intervention.
The technical implementation of this vulnerability demonstrates poor input validation and error handling practices within the telnet option processing code. The software fails to properly validate or sanitize incoming telnet options before attempting to process them, leading to the NULL pointer dereference condition. This type of vulnerability is particularly concerning as it can be exploited through network-based attacks without requiring authentication or privileged access. Organizations using this telnet server software should implement immediate mitigations including applying vendor patches, disabling unnecessary telnet services, and implementing network segmentation to limit exposure. The vulnerability also highlights the importance of proper memory management practices and input validation in network services, aligning with ATT&CK technique T1499.004 for network denial of service attacks and emphasizing the need for robust error handling in server applications.