CVE-2004-2388 in AIX
Summary
by MITRE
rexecd for AIX 4.3.3 does not properly use a local copy of the pwd structure when calling getpwnam, which may cause the structure to be overwritten by the authenticate function and assign privileges to the wrong user.
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Analysis
by VulDB Data Team • 06/27/2019
The vulnerability described in CVE-2004-2388 affects the rexecd service on AIX 4.3.3 systems, representing a critical privilege escalation flaw that stems from improper handling of user authentication data structures. This issue specifically involves the interaction between the rexecd daemon and the getpwnam function, which is responsible for retrieving user account information from the system's password database. The flaw occurs when the rexecd service attempts to authenticate remote users while processing incoming connections, creating a scenario where the local pwd structure is not properly isolated from the authentication process.
The technical root cause of this vulnerability lies in the improper use of the pwd structure within the rexecd implementation. When the service calls getpwnam to retrieve user information, it fails to maintain a local copy of the structure that is separate from the authentication function's working memory space. This design flaw allows the authenticate function to potentially overwrite the pwd structure contents, leading to a situation where the system may inadvertently assign privileges to an incorrect user account. The vulnerability specifically manifests when remote users attempt to establish connections through the rexecd service, as the authentication routine processes user credentials in a manner that exposes the pwd structure to unauthorized modifications.
The operational impact of this vulnerability is severe and directly affects system security through privilege escalation capabilities. An attacker who successfully exploits this flaw could potentially gain unauthorized access to system resources and elevate their privileges to those of another user, particularly one with higher administrative rights. This vulnerability undermines the fundamental security model of the AIX operating system by allowing misattribution of user privileges during the authentication process, potentially enabling unauthorized system access and data compromise. The flaw affects the integrity of the user authentication mechanism, making it possible for malicious actors to impersonate legitimate users and gain unauthorized access to sensitive system resources.
Mitigation strategies for this vulnerability should focus on immediate system updates and configuration hardening measures. The primary recommendation involves applying the appropriate AIX security patches provided by IBM to address the specific implementation flaw in the rexecd service. System administrators should also consider disabling the rexecd service entirely if it is not essential for system operations, as this eliminates the attack surface associated with the vulnerable component. Additionally, implementing proper network segmentation and access controls can help limit the exposure of systems running affected versions of AIX. From a compliance perspective, this vulnerability aligns with CWE-248, which addresses the improper handling of exception conditions, and represents a significant concern for organizations following security frameworks such as the NIST Cybersecurity Framework or ISO 27001 standards. The ATT&CK framework categorizes this issue under privilege escalation techniques, specifically targeting the use of insecure service configurations and authentication bypass methods that could be leveraged by adversaries to gain unauthorized system access and maintain persistent presence within affected environments.