CVE-2003-0671 in tcpflow
Summary
by MITRE
Format string vulnerability in tcpflow, when used in a setuid context, allows local users to execute arbitrary code via the device name argument, as demonstrated in Sustworks IPNetSentryX and IPNetMonitorX the setuid program RunTCPFlow.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/26/2019
The vulnerability described in CVE-2003-0671 represents a critical format string flaw in tcpflow utility when operating in setuid mode, creating a significant security risk for network monitoring applications. This vulnerability specifically affects tcpflow versions that are compiled with setuid privileges, allowing local attackers to exploit the format string vulnerability through the device name argument. The exploit demonstrates how seemingly benign network monitoring tools can become dangerous when improperly handled with elevated privileges. The vulnerability is particularly concerning because it leverages the setuid mechanism that is commonly used in network monitoring tools to ensure proper network interface access while maintaining elevated privileges. When tcpflow is invoked with setuid permissions and processes user-supplied device name arguments without proper validation, it creates an opportunity for format string exploitation that can be used to execute arbitrary code on the system.
The technical implementation of this vulnerability stems from improper input handling within tcpflow's argument processing, specifically when the device name parameter is passed to a format string function such as printf or fprintf. The flaw occurs because the program directly uses user-provided device name strings as format specifiers without sanitizing them first, allowing attackers to inject format specifiers that can manipulate the program's execution flow. This type of vulnerability falls under the Common Weakness Enumeration category CWE-134, which specifically addresses the use of format strings with user-controlled data. The attack vector is particularly effective because tcpflow is designed to run with elevated privileges to access network interfaces, making the potential impact of code execution significantly more severe than typical format string vulnerabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary code with the privileges of the setuid tcpflow process, which typically operates with root-level access. This creates a pathway for attackers to gain complete system control, potentially leading to data breaches, system compromise, and further lateral movement within the network. The vulnerability is particularly dangerous when exploited in conjunction with applications like Sustworks IPNetSentryX and IPNetMonitorX that rely on the RunTCPFlow setuid program to perform network monitoring functions. These commercial applications may not properly validate input parameters, making them susceptible to exploitation through the underlying tcpflow vulnerability. The exploitation process typically involves crafting a malicious device name argument containing format specifiers that can be used to overwrite program memory, potentially leading to stack-based buffer overflows or direct code execution.
Mitigation strategies for this vulnerability require immediate patching of tcpflow to properly sanitize user input before using it in format string functions, ensuring that all user-supplied arguments are validated and escaped appropriately. Organizations should implement privilege separation techniques to avoid running network monitoring tools with setuid privileges when possible, instead using alternative approaches such as capability-based permissions or dedicated monitoring daemons with minimal required privileges. System administrators should also conduct thorough security assessments of all setuid programs to identify similar vulnerabilities, particularly in network monitoring and packet capture utilities. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques, specifically focusing on the use of vulnerable setuid binaries as a means to gain elevated system access. Additionally, implementing proper input validation, using secure coding practices such as vsnprintf instead of sprintf, and regularly updating network monitoring tools can significantly reduce the risk of exploitation. Organizations should also consider network segmentation and monitoring to detect suspicious activity that might indicate exploitation attempts, as the vulnerability can be used as a foothold for more extensive attacks within the network infrastructure.