Source: cve@mitre.org
Buffer overflow in the syslog daemon for Solaris 2.6 through 9 allows remote attackers to cause a denial of service (syslogd crash) and possibly execute arbitrary code via long syslog UDP packets.
Solaris syslogd is vulnerable to a buffer overflow, allowing remote attackers to crash the service and potentially execute arbitrary code. This vulnerability, exploitable via oversized UDP packets, could lead to a denial-of-service or complete system compromise. Successful exploitation could allow attackers to gain unauthorized access and control of affected systems.
Step 1: Payload Delivery: The attacker crafts a UDP packet containing a syslog message exceeding the buffer size allocated within the syslogd process. The packet is sent to the UDP port used by syslogd (typically port 514).
Step 2: Packet Reception: The syslogd daemon receives the oversized UDP packet.
Step 3: Buffer Overflow: The syslogd attempts to write the received syslog message into a fixed-size buffer without checking the message's length. The oversized message overflows the buffer, overwriting adjacent memory locations.
Step 4: Potential Code Execution/DoS: Depending on the overwritten memory, the overflow can either cause a denial-of-service (DoS) by crashing the syslogd process or, if the return address is overwritten with a controlled value, allow for arbitrary code execution.
The vulnerability lies within the syslogd daemon's handling of UDP packets. Specifically, the daemon fails to properly validate the size of incoming syslog messages before writing them to a fixed-size buffer. A malicious actor can craft a UDP packet containing a syslog message larger than the allocated buffer. This leads to a buffer overflow, overwriting adjacent memory regions. The overwritten memory can contain critical data, including the program's return address. By carefully crafting the oversized packet, an attacker can overwrite the return address with the address of malicious code (shellcode), leading to arbitrary code execution. The root cause is a lack of bounds checking on the input data size before the data is copied into the buffer. This allows for the overflow.
While specific APT groups are not definitively linked to this specific CVE, the ease of exploitation and potential for remote code execution makes it a target for various threat actors. This vulnerability is likely used by opportunistic attackers and could be incorporated into more sophisticated attacks. The age of the vulnerability suggests it might be used in conjunction with other exploits. This vulnerability is not listed on the CISA KEV at this time.
Network traffic analysis: Monitor for unusually large UDP packets sent to the syslog port (typically 514).
Log analysis: Examine syslog logs for signs of crashes or unexpected behavior, especially around the time of potential exploitation attempts.
Intrusion Detection Systems (IDS): Deploy IDS rules that detect oversized UDP packets or specific patterns associated with the exploit.
Forensic analysis: Examine memory dumps of the syslogd process after a crash for evidence of buffer overflows.
File Integrity Monitoring: Monitor the syslogd executable for any unexpected modifications.
Patching: Apply the appropriate security patches provided by Sun Microsystems (now Oracle) for the affected Solaris versions. This is the primary and most effective remediation.
Network Segmentation: Isolate systems running vulnerable versions of Solaris in a separate network segment to limit the attack surface.
Input Validation: Implement input validation at the network level (e.g., firewalls) to filter out oversized UDP packets.
Host-Based Intrusion Detection System (HIDS): Deploy a HIDS to monitor for suspicious activity on the affected systems.
Least Privilege: Ensure the syslogd process runs with the least necessary privileges.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.