Source: cve@mitre.org
Buffer overflow in AIX and Solaris "gethostbyname" library call allows root access through corrupt DNS host names.
Critical vulnerability allowing for remote root access on vulnerable AIX and Solaris systems. Exploitation involves crafting a malicious DNS hostname that overflows a buffer within the gethostbyname library call, enabling attackers to execute arbitrary code with elevated privileges and compromise the entire system.
Step 1: DNS Poisoning/Crafting Malicious Hostname: The attacker either poisons the DNS cache of a vulnerable system or crafts a malicious DNS hostname that, when resolved, exceeds the buffer size within gethostbyname.
Step 2: Triggering the Vulnerability: A user or process on the vulnerable system attempts to resolve the malicious hostname. This triggers the vulnerable gethostbyname function.
Step 3: Buffer Overflow: The gethostbyname function processes the malicious hostname, exceeding the allocated buffer size. This overwrites adjacent memory, including the return address.
Step 4: Code Execution: The overwritten return address points to attacker-controlled code (e.g., shellcode) injected into the buffer. The program jumps to this code.
Step 5: Privilege Escalation: The attacker's shellcode executes with the privileges of the process calling gethostbyname (typically root), granting the attacker full control of the system.
The vulnerability lies within the gethostbyname function, a core library call responsible for resolving hostnames to IP addresses. The root cause is a buffer overflow vulnerability. When processing a malicious DNS hostname, the function fails to properly validate the size of the input, leading to an overflow of a fixed-size buffer. This allows an attacker to overwrite adjacent memory regions, including the return address, and redirect program execution to attacker-controlled code (e.g., a shellcode). The lack of input validation and the use of a fixed-size buffer are the primary flaws. The vulnerability is exacerbated by the fact that gethostbyname is often called by privileged processes, granting the attacker root-level access upon successful exploitation.
Due to the age of this vulnerability, specific APT groups are not directly linked to its exploitation. However, any threat actor targeting legacy systems could potentially leverage this vulnerability. This CVE is not listed in the CISA KEV catalog.
Monitor DNS traffic for unusually long or malformed hostnames.
Analyze system logs for suspicious activity related to DNS resolution, such as repeated failures or unexpected errors.
Examine core dumps or memory dumps for evidence of buffer overflows in the gethostbyname function.
Network Intrusion Detection Systems (NIDS) can be configured to detect malicious DNS traffic patterns.
File integrity monitoring to detect changes to system binaries or libraries.
Patch the affected systems with the latest security updates from the vendor.
Implement a robust DNS security strategy, including DNSSEC, to prevent DNS poisoning.
Restrict access to vulnerable systems and segregate them from critical infrastructure.
Implement network segmentation to limit the impact of a successful exploit.
Regularly scan systems for vulnerabilities and apply security best practices.
Consider using a Web Application Firewall (WAF) to filter malicious DNS requests.