CVE-2002-0437 in SMS Server Tools
Summary
by MITRE
Smsd in SMS Server Tools (SMStools) before 1.4.8 allows remote attackers to execute arbitrary commands via shell metacharacters (backquotes) in message text, as described with the term "string format vulnerability" by some sources.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability identified as CVE-2002-0437 affects the smsd component of SMS Server Tools, a widely used open-source SMS gateway software that facilitates communication between cellular networks and computer systems. This flaw exists in versions prior to 1.4.8 and represents a critical security weakness that enables remote attackers to execute arbitrary commands on the affected system. The vulnerability stems from insufficient input validation and sanitization within the smsd daemon, which processes incoming SMS messages and routes them to appropriate destinations. When the system receives an SMS message containing specially crafted shell metacharacters, particularly backquotes, the application fails to properly escape or filter these characters before processing them within shell contexts.
This vulnerability constitutes a classic command injection flaw that aligns with CWE-77 and CWE-94 categories, representing a form of shell injection where attacker-controlled data is interpreted as shell commands. The attack vector operates through the manipulation of message text fields that are processed by the smsd service without adequate sanitization. When the system encounters backquote characters in SMS content, these are interpreted by the shell as command substitution operators, allowing attackers to execute arbitrary commands with the privileges of the smsd process. The operational impact extends beyond simple command execution as the vulnerability can be exploited remotely without authentication, making it particularly dangerous for systems that are exposed to the internet or untrusted networks. Attackers can leverage this weakness to gain full control over the affected system, potentially leading to data theft, system compromise, or use as a pivot point for further attacks within the network infrastructure.
The exploitation of this vulnerability demonstrates a fundamental flaw in input handling and privilege separation within the smsd application. Systems running vulnerable versions of SMStools are at risk of complete compromise since the smsd service typically runs with elevated privileges to manage modem connections and system resources. The vulnerability's severity is amplified by the fact that it can be triggered through simple SMS messages, making it accessible to attackers with minimal technical expertise. Organizations using SMStools for critical communications or those operating in regulated environments face significant compliance and security implications, as this vulnerability violates principles of secure coding and input validation. The flaw also relates to ATT&CK technique T1059.007 for Command and Scripting Interpreter: Unix Shell, highlighting how attackers can leverage shell-based command execution to achieve their objectives.
Mitigation strategies for CVE-2002-0437 primarily involve immediate upgrading to SMStools version 1.4.8 or later, which includes proper input sanitization and escaping mechanisms. System administrators should also implement network segmentation to limit access to the smsd service, deploy firewall rules to restrict incoming SMS traffic, and consider implementing additional input validation layers. The vulnerability serves as a reminder of the critical importance of secure coding practices, particularly in applications that process untrusted input from external sources. Organizations should conduct regular security assessments of their SMS infrastructure and maintain up-to-date monitoring for similar vulnerabilities in other communication tools and systems. Additionally, implementing proper privilege separation and least-privilege principles for the smsd service can significantly reduce the potential impact of successful exploitation attempts.