CVE-2016-20014 in pam_tacplus
Summary
by MITRE • 04/21/2022
In pam_tacplus.c in pam_tacplus before 1.4.1, pam_sm_acct_mgmt does not zero out the arep data structure.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/28/2022
The vulnerability identified as CVE-2016-20014 affects the pam_tacplus module, a Pluggable Authentication Module implementation for TACACS+ authentication. This module serves as a bridge between the Linux PAM framework and TACACS+ protocol, which is widely used for centralized network access control. The issue resides in the pam_tacplus.c source file within the pam_tacplus library version prior to 1.4.1, specifically impacting the pam_sm_acct_mgmt function that handles account management operations.
The technical flaw manifests in the pam_sm_acct_mgmt function's failure to properly initialize or zero out the arep data structure before use. This data structure contains account management response information that is processed during authentication and authorization operations. When memory is not properly cleared, sensitive data from previous operations may remain in memory locations, creating potential information leakage vulnerabilities. The failure to zero out memory allocations creates a classic memory corruption vulnerability that can expose confidential information to unauthorized parties.
The operational impact of this vulnerability extends beyond simple information disclosure. Attackers who can exploit this weakness may gain access to residual authentication data, session information, or other sensitive account management details that were previously processed by the module. This could potentially enable credential harvesting, session hijacking, or further exploitation attempts against the authentication infrastructure. The vulnerability particularly affects systems that rely on TACACS+ for network device access control, where account management operations are frequently performed. Organizations using network devices such as routers, switches, and firewalls that depend on TACACS+ authentication for privileged access are at risk when running vulnerable versions of pam_tacplus.
This vulnerability aligns with CWE-1288, which addresses the improper zeroing of sensitive data, and falls under the broader category of information exposure vulnerabilities. From an attack perspective, this issue can be categorized under the ATT&CK technique T1552.001, focusing on credentials from password storage, as it potentially exposes authentication-related information that could be leveraged for privilege escalation or unauthorized access. The vulnerability represents a memory management error that could be exploited by attackers with access to the system to extract sensitive information from memory dumps or through side-channel attacks. Organizations should prioritize updating to pam_tacplus version 1.4.1 or later to address this issue, as the fix ensures proper memory initialization and eliminates the risk of sensitive data leakage through residual information in the arep data structure.