CVE-2011-1946 in libgnomesu
Summary
by MITRE
gnomesu-pam-backend in libgnomesu 1.0.0 prints an error message but proceeds with the non-error code path upon failure of the setgid or setuid function, which allows local users to gain privileges by leveraging access to two unprivileged user accounts, and running many processes under one of these accounts.
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Analysis
by VulDB Data Team • 11/14/2021
The vulnerability identified as CVE-2011-1946 resides within the gnomesu-pam-backend component of libgnomesu version 1.0.0, representing a critical privilege escalation flaw that undermines the security model of Unix-like operating systems. This issue manifests when the system attempts to elevate privileges through setgid or setuid operations, which are fundamental mechanisms for granting temporary elevated permissions to user processes. The vulnerability operates under CWE-276, specifically addressing improper privilege management where the system fails to properly handle failure conditions in privilege elevation routines. The flaw enables attackers to exploit a race condition or improper error handling in the privilege escalation process.
The technical implementation of this vulnerability involves the gnomesu-pam-backend component failing to properly validate the success of setuid or setgid system calls during the privilege escalation process. When these system calls fail, the component should terminate the operation and not proceed with privilege elevation. However, the code continues execution along a non-error code path despite the failure, creating a window where privilege escalation can occur. This behavior directly violates the principle of least privilege and represents a classic example of error handling failure that allows privilege escalation attacks.
The operational impact of this vulnerability is significant for systems utilizing GNOME desktop environments and the libgnomesu library for privilege escalation. Local attackers with access to two unprivileged user accounts can leverage this flaw to gain elevated privileges by running processes under one of these accounts. The attack requires minimal privileges and can be executed through a simple process of running multiple processes under one account while exploiting the flawed privilege escalation mechanism. This vulnerability essentially provides a backdoor path for privilege escalation that bypasses normal access controls and authentication mechanisms. The attack vector is particularly concerning because it does not require network access or complex exploitation techniques.
Systems affected by CVE-2011-1946 typically include Linux distributions running GNOME desktop environments with libgnomesu version 1.0.0 or earlier, particularly those that utilize the gnomesu utility for privilege escalation. The vulnerability aligns with ATT&CK technique T1068, which describes privilege escalation through the exploitation of system vulnerabilities. Organizations running affected systems are at risk of unauthorized privilege escalation, potentially allowing attackers to gain root access or elevated privileges to perform actions such as modifying system files, installing malware, or accessing sensitive data. The vulnerability can be exploited by any local user who has access to two separate unprivileged accounts, making it particularly dangerous in multi-user environments.
Mitigation strategies for this vulnerability involve immediate patching of the libgnomesu library to version 1.0.1 or later, which contains the necessary fixes to properly handle setuid/setgid failures. System administrators should also implement additional security measures such as monitoring for unauthorized privilege escalation attempts and ensuring that only trusted users have access to multiple accounts that could be exploited. The fix addresses the core issue by ensuring that when setuid or setgid operations fail, the process terminates immediately rather than proceeding with potentially compromised privilege levels. Additionally, organizations should review their privilege escalation mechanisms and implement proper error handling to prevent similar issues in other components. The vulnerability demonstrates the importance of robust error handling in security-critical code and highlights the need for comprehensive security testing of privilege management functions.