Source: cve@mitre.org
Vulnerability in in.rlogind in SunOS 4.0.3 and 4.0.3c allows local users to gain root privileges.
CVE-1999-1212 describes a critical vulnerability in the in.rlogind service on SunOS 4.0.3 and 4.0.3c, allowing local users to escalate privileges to root. Successful exploitation grants attackers complete control over the compromised system, leading to severe data breaches and system compromise.
Step 1: Vulnerability Trigger: The attacker connects to the in.rlogind service on the target SunOS system.
Step 2: Malicious Input: The attacker crafts a specially crafted username or password, exceeding the allocated buffer size within the in.rlogind service.
Step 3: Buffer Overflow: The oversized input overwrites adjacent memory locations on the stack, including the return address.
Step 4: Shellcode Injection (Optional): The attacker may include shellcode within the malicious input, or the overwritten return address points to existing code that can be leveraged for privilege escalation.
Step 5: Control Hijack: When in.rlogind attempts to return from the vulnerable function, the overwritten return address directs execution to the attacker's shellcode (or a pre-existing code path).
Step 6: Privilege Escalation: The shellcode (or leveraged code) executes with root privileges, granting the attacker complete control of the system.
The vulnerability stems from a buffer overflow within the in.rlogind service. Specifically, the service fails to properly validate the length of user-supplied input, such as the username or password, when handling authentication requests. This allows an attacker to craft a malicious input that overwrites critical memory regions, including the return address on the stack. By controlling the return address, the attacker can redirect program execution to arbitrary code, typically a shellcode payload, granting them root privileges. The root cause is a lack of bounds checking on input data, leading to a classic stack-based buffer overflow.
Due to the age of the vulnerability, it is unlikely to be directly associated with specific APT groups. However, any attacker with basic skills could exploit it. This type of vulnerability is often used in conjunction with other exploits to achieve a foothold and escalate privileges. CISA KEV status: Not Applicable due to the age of the vulnerability and the lack of modern systems affected.
Monitor system logs for suspicious activity related to in.rlogind, such as failed login attempts with unusually long usernames or passwords.
Analyze network traffic for connections to the rlogin port (514/tcp) from unexpected sources or with unusual payloads.
Implement host-based intrusion detection systems (HIDS) to monitor for changes to system files and processes associated with in.rlogind.
Examine core dumps or crash logs for evidence of buffer overflows or memory corruption related to in.rlogind.
Patching: The most effective remediation is to upgrade to a supported operating system version that addresses the vulnerability. Since this is a very old vulnerability, patching is not an option.
Disable rlogin: If rlogin is not required, disable the in.rlogind service. This eliminates the attack surface.
Network Segmentation: Isolate vulnerable systems on a separate network segment to limit the impact of a successful exploit.
Implement Strong Authentication: Enforce strong password policies and multi-factor authentication (MFA) where possible, even if rlogin is used.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.