CVE-2011-2489 in opie
Summary
by MITRE
Multiple off-by-one errors in opiesu.c in opiesu in OPIE 2.4.1-test1 and earlier might allow local users to gain privileges via a crafted command line.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability identified as CVE-2011-2489 represents a critical security flaw within the OPIE (One-Time Passwords for Unix) authentication system version 2.4.1-test1 and earlier. This issue manifests through multiple off-by-one errors located in the opiesu.c source file, which serves as a crucial component in the privilege escalation mechanism of the OPIE system. The vulnerability specifically affects the command line argument processing functionality that is integral to how users authenticate and gain elevated privileges within Unix-based systems. These off-by-one errors occur when the program fails to properly validate the boundaries of array indices or string lengths during command line parsing operations.
The technical nature of this vulnerability stems from improper boundary checking in memory management operations within the opiesu utility. When users provide command line arguments to the opiesu program, the flawed code does not correctly handle the edge cases where array access attempts occur at positions that exceed the allocated memory boundaries. This programming error creates a scenario where maliciously crafted command line inputs can cause buffer overflows or memory corruption, potentially allowing local attackers to manipulate the program execution flow. The vulnerability specifically targets the privilege escalation path that OPIE uses to transition from regular user privileges to elevated system privileges, making it particularly dangerous for systems where OPIE is deployed as an authentication mechanism.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it represents a fundamental flaw in how the authentication system handles user input validation. Local users who can execute the opiesu utility with sufficient privileges can exploit this vulnerability to gain elevated system access, potentially allowing them to execute arbitrary code with root privileges. The implications are significant for Unix-based systems that rely on OPIE for enhanced authentication security, as attackers can leverage this vulnerability to bypass the intended security controls. This flaw undermines the core security assumptions of the OPIE system, potentially allowing unauthorized access to sensitive system resources and data.
Security researchers categorize this vulnerability under CWE-129, which specifically addresses "Improper Validation of Array Index," and CWE-121, covering "Stack-based Buffer Overflow." The exploitability of this vulnerability aligns with ATT&CK technique T1068, which describes "Exploitation for Privilege Escalation" and demonstrates how local attackers can leverage software vulnerabilities to gain higher system privileges. The vulnerability's classification as a local privilege escalation issue means that it requires the attacker to already have access to the system, but once exploited, it can provide complete system compromise. Organizations should consider implementing immediate mitigations including updating to patched versions of OPIE, disabling unnecessary usage of the opiesu utility, and monitoring system logs for suspicious command line argument patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper input validation and boundary checking in security-critical applications, particularly those handling user-provided data in privilege escalation contexts.