CVE-2011-2490 in opie
Summary
by MITRE
opielogin.c in opielogin in OPIE 2.4.1-test1 and earlier does not check the return value of the setuid system call, which allows local users to gain privileges by arranging for an account to already be running its maximum number of processes.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability described in CVE-2011-2490 resides within the opielogin component of the OPIE (One-Time Passwords for Internet Explorer) authentication system version 2.4.1-test1 and earlier. This flaw represents a critical privilege escalation vulnerability that exploits improper error handling within the authentication process. The issue specifically affects the opielogin.c source file where the setuid system call return value is not properly validated, creating a potential pathway for local attackers to elevate their privileges on affected systems.
The technical flaw stems from the failure to check the return value of the setuid system call during the authentication process. When a user attempts to log in through the opielogin mechanism, the system should verify that the setuid operation successfully transitions the process to the target user context. However, in vulnerable versions, this validation is omitted entirely, allowing the authentication process to continue regardless of whether the setuid call succeeded or failed. This oversight creates a scenario where malicious users can manipulate the system's process limits to force a failure condition that ultimately results in privilege escalation.
The operational impact of this vulnerability is significant as it enables local attackers to gain elevated privileges on systems running vulnerable versions of OPIE. The attack vector requires the attacker to have access to an account that is already running at its maximum number of processes, which is a relatively common condition on busy systems. When the system attempts to create a new process for authentication while the account has reached its process limit, the setuid call fails but the authentication process continues, potentially allowing the attacker to execute code with elevated privileges. This represents a direct violation of the principle of least privilege and undermines the fundamental security model of the authentication system.
This vulnerability maps to CWE-252, which describes an unchecked return value, and demonstrates poor error handling practices in security-critical code. From an attacker's perspective, this flaw aligns with techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically targeting the use of insecure system calls and process manipulation. The vulnerability also reflects broader issues in Unix-like system security where improper validation of system calls can create exploitable conditions. Organizations should implement immediate mitigations including updating to patched versions of OPIE, enforcing strict process limits, and monitoring for unauthorized privilege escalation attempts. System administrators should also consider implementing additional security controls such as mandatory access controls and process monitoring to detect anomalous behavior that might indicate exploitation attempts. The vulnerability highlights the critical importance of proper error handling in security-sensitive code and serves as a reminder that even seemingly minor oversights in system call validation can result in severe privilege escalation consequences.