Source: cve@mitre.org
Format string vulnerability in LICQ 1.2.6, 1.0.3 and possibly other versions allows remote attackers to perform unknown actions via format string specifiers.
LICQ, a popular instant messaging client, is vulnerable to a format string vulnerability, allowing remote attackers to execute arbitrary code. Successful exploitation could lead to complete system compromise, including data theft and denial of service, by crafting malicious messages containing format string specifiers.
Step 1: Payload Delivery: The attacker sends a specially crafted message to a LICQ user. This message contains format string specifiers (e.g., %x, %s, %n).
Step 2: Message Processing: The LICQ client receives and processes the malicious message.
Step 3: Vulnerable Function Call: The client passes the attacker-controlled message, including the format string specifiers, to a function that uses format string functionality (e.g., printf, fprintf) without proper sanitization.
Step 4: Memory Manipulation: The format string specifiers are interpreted, allowing the attacker to read from or write to arbitrary memory locations. This can lead to information disclosure, code execution, or denial of service.
Step 5: Exploitation: Depending on the attacker's goals, they can use the memory manipulation capabilities to achieve various objectives, such as leaking sensitive information, overwriting critical data, or injecting and executing malicious code.
The vulnerability stems from improper handling of user-supplied input within the LICQ application. Specifically, the software fails to sanitize user-provided data before passing it to functions that interpret format string specifiers (e.g., printf, fprintf). This allows an attacker to inject format string directives (like %x, %s, %n) into a message. These directives can then be used to read from or write to arbitrary memory locations, leading to information disclosure, code execution, or denial of service. The root cause is the lack of input validation and sanitization of user-controlled data before it's used in format string operations. This allows the attacker to control the arguments passed to the format string function, leading to memory manipulation.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific APT groups. However, any threat actor with basic skills could exploit this vulnerability. The vulnerability's potential for remote code execution makes it a high-value target. Not listed on CISA KEV.
Network traffic analysis: Examine network traffic for messages containing format string specifiers (e.g., %x, %s, %n) within LICQ protocol communications.
Log analysis: Review LICQ client logs for unusual behavior, errors, or crashes that may indicate exploitation attempts.
Host-based intrusion detection systems (HIDS): Monitor for suspicious process behavior, such as unexpected memory access or code execution within the LICQ process.
Memory forensics: Analyze memory dumps of the LICQ process for evidence of format string exploitation, such as modified memory regions or injected code.
Upgrade to a patched version of LICQ or a secure alternative. Since the software is old, this is the primary and most effective solution.
Implement input validation: Ensure that all user-supplied input is properly validated and sanitized before being used in format string functions.
Use secure coding practices: Avoid using format string functions with user-controlled input whenever possible. If unavoidable, use safe alternatives or carefully sanitize the input.
Network segmentation: Isolate systems running vulnerable software to limit the impact of a successful exploit.
Regular security audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.