Source: cve@mitre.org
Buffer overflow in syslog utility allows local or remote attackers to gain root privileges.
Syslog, a critical system logging utility, is vulnerable to a buffer overflow, allowing attackers to gain root privileges. This vulnerability, exploitable locally or remotely, can lead to complete system compromise and data exfiltration. Immediate patching and robust monitoring are crucial to mitigate this severe risk.
Step 1: Payload Delivery: An attacker crafts a malicious log message exceeding the allocated buffer size within the syslog utility. This message can be sent locally (e.g., via a compromised application) or remotely (e.g., via a network connection to the syslog daemon).
Step 2: Buffer Overflow Trigger: The syslog utility receives the oversized log message and attempts to process it. Due to the lack of input validation, the message is copied into a fixed-size buffer.
Step 3: Memory Corruption: The oversized data overwrites the buffer and spills into adjacent memory regions, including the stack. This overwrite corrupts critical data, such as the return address of the function currently executing.
Step 4: Control Hijack: The attacker's crafted payload overwrites the return address with the address of their injected shellcode.
Step 5: Code Execution: When the function returns, the CPU jumps to the attacker-controlled shellcode, executing it with the privileges of the syslog daemon (typically root).
Step 6: Privilege Escalation: The attacker's shellcode executes, granting them root access and complete control over the compromised system.
The vulnerability lies within the syslog utility's handling of log messages. Specifically, the code responsible for processing incoming log data from various sources (local applications, remote hosts) fails to properly validate the size of the input before copying it into a fixed-size buffer. This leads to a buffer overflow when a crafted log message, exceeding the buffer's capacity, overwrites adjacent memory regions. This overwrite can corrupt critical data structures, including the return address on the stack. By carefully crafting the malicious log message, an attacker can overwrite the return address with the address of their injected shellcode, allowing them to execute arbitrary code with the privileges of the syslog daemon, typically root. The root cause is a lack of bounds checking on input data, a common coding error that allows for the exploitation of the stack-based buffer overflow.
This vulnerability is a classic and could be leveraged by any threat actor. While no specific APTs are directly linked to only this CVE, it's a common initial access vector. It is a prime candidate for exploitation by less sophisticated actors due to the availability of public exploits. CISA KEV status: Not listed, but the underlying vulnerability type is a common target.
Monitor syslog logs for unusually long or malformed log messages, especially those originating from untrusted sources.
Analyze network traffic for suspicious connections to the syslog port (typically UDP/514 or TCP/601).
Implement host-based intrusion detection systems (HIDS) to monitor for suspicious file modifications or process behavior related to syslog.
Use file integrity monitoring (FIM) to detect unauthorized changes to syslog binaries and configuration files.
Examine system logs for unexpected process creation or command execution, particularly those initiated by the syslog daemon.
Look for evidence of shellcode execution in memory using memory forensics tools.
Apply security patches provided by the vendor immediately. Prioritize patching systems that are exposed to the network.
Implement input validation to ensure that all data received by the syslog utility is properly sanitized and validated before processing.
Use a modern syslog implementation that incorporates security features like bounds checking and address space layout randomization (ASLR).
Restrict network access to the syslog port (UDP/514 or TCP/601) to only trusted hosts.
Implement a strong password policy and multi-factor authentication (MFA) for all user accounts.
Regularly update and maintain all system software, including the operating system and all installed applications.
Implement a robust logging and monitoring solution to detect and respond to suspicious activity.
Consider using a host-based intrusion detection system (HIDS) to monitor for malicious activity.