CVE-2020-10744 in Ansible Engine
Summary
by MITRE
An incomplete fix was found for the fix of the flaw CVE-2020-1733 ansible: insecure temporary directory when running become_user from become directive. The provided fix is insufficient to prevent the race condition on systems using ACLs and FUSE filesystems. Ansible Engine 2.7.18, 2.8.12, and 2.9.9 as well as previous versions are affected and Ansible Tower 3.4.5, 3.5.6 and 3.6.4 as well as previous versions are affected.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability described in CVE-2020-10744 represents a critical security flaw in Ansible's privilege escalation mechanism that stems from an inadequate remediation of a previously identified issue. This vulnerability specifically affects the become_user directive functionality within Ansible's execution engine, where the original fix for CVE-2020-1733 failed to address all potential attack vectors. The flaw manifests when Ansible attempts to create temporary directories during privilege escalation operations, creating a race condition that can be exploited by malicious actors to gain unauthorized access to system resources. The incomplete nature of the fix becomes particularly problematic on systems that utilize Access Control Lists and FUSE filesystems, where the traditional security mechanisms are insufficient to prevent unauthorized directory access.
The technical implementation of this vulnerability occurs within Ansible's privilege escalation handling code, where temporary directories are created without proper synchronization mechanisms to prevent concurrent access. When Ansible executes commands with elevated privileges using the become directive, it creates temporary files and directories in locations that can be manipulated by attackers. The race condition arises because the system does not adequately secure these temporary directories before they are accessed by the elevated process. This flaw is particularly concerning because it leverages the inherent permissions and access controls of the underlying operating system, specifically when ACLs and FUSE filesystems are present, which can create additional attack surfaces that the original fix did not account for.
The operational impact of this vulnerability extends beyond simple privilege escalation attacks, as it can enable attackers to execute arbitrary code with elevated privileges on target systems. Systems running affected versions of Ansible Engine and Ansible Tower are at risk of unauthorized access and potential system compromise when performing automated tasks that involve privilege escalation. The vulnerability affects multiple versions including Ansible Engine 2.7.18, 2.8.12, and 2.9.9 along with their respective Ansible Tower counterparts, indicating a widespread exposure across different release branches. This creates significant operational risk for organizations that rely on Ansible for system management and automation, as attackers could exploit this vulnerability to gain root access or administrative privileges on managed systems.
Organizations should implement immediate mitigations including upgrading to patched versions of Ansible Engine and Ansible Tower that properly address this race condition. The recommended approach involves applying the official security patches that provide proper directory creation and access control mechanisms that prevent concurrent access during privilege escalation operations. Additionally, system administrators should consider implementing additional controls such as restricting the use of become directives where possible, implementing proper filesystem permissions, and monitoring for unauthorized access attempts to temporary directories. This vulnerability aligns with CWE-362, which describes race conditions that can lead to privilege escalation, and maps to ATT&CK technique T1059.001 for execution through command and scripting interpreter, where attackers could leverage this vulnerability to execute malicious code with elevated privileges. The security community has identified this as a critical vulnerability requiring immediate attention due to its potential for privilege escalation and system compromise.