CVE-1999-0651 in Host
Summary
by MITRE
The rsh/rlogin service is running.
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Analysis
by VulDB Data Team • 10/24/2025
The rsh and rlogin services represent fundamental security vulnerabilities in networked computing environments, as they operate without proper authentication mechanisms and transmit credentials in plaintext. These services were designed in the early days of unix systems for remote administration but have since been recognized as inherently insecure due to their lack of encryption and weak authentication protocols. The presence of these services on a system creates a significant attack surface that malicious actors can exploit to gain unauthorized access to networked resources.
The technical flaw inherent in rsh and rlogin implementations stems from their reliance on the .rhosts file for authentication, which operates on a simple trust model where any host listed in the file can access the system without additional verification. This approach completely bypasses modern security standards and creates a dangerous environment where compromised hosts can immediately access other systems. The services also transmit user credentials and commands in clear text across the network, making them vulnerable to interception through packet sniffing techniques. This plaintext transmission directly violates security best practices outlined in standards such as cwe-312 and cwe-319, which specifically address the exposure of sensitive information during transmission.
The operational impact of running these services extends far beyond simple credential exposure, as they provide attackers with persistent access to target systems and enable lateral movement within networks. Once an attacker gains access through these services, they can escalate privileges, establish backdoors, and conduct reconnaissance without detection. The services also create audit trail challenges since they do not properly log authentication attempts or maintain session records. According to att&ck framework technique t1075, adversaries often leverage legitimate remote access tools to move laterally within networks, making rsh and rlogin prime targets for exploitation. The services can also be used to establish persistent access through automated scripts that maintain connections across system reboots.
Mitigation strategies for these vulnerabilities involve immediate service removal and replacement with secure alternatives such as ssh for remote administration. Organizations should implement network segmentation to isolate systems running these services and conduct thorough vulnerability assessments to identify all instances. Security monitoring should include detection of rsh and rlogin traffic on network segments, as these services typically operate on well-known ports 512 and 513. The implementation of ssh keys with proper access controls provides a secure replacement that maintains necessary functionality while eliminating the plaintext transmission risks. Additionally, organizations should review and remove any automated scripts or processes that rely on these deprecated services to prevent accidental activation and ensure complete remediation of the vulnerability.