CVE-2021-20253 in Ansible Tower
Summary
by MITRE • 03/10/2021
A flaw was found in ansible-tower. The default installation is vulnerable to Job Isolation escape allowing an attacker to elevate the privilege from a low privileged user to the awx user from outside the isolated environment. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2021-20253 resides within the ansible-tower application, specifically manifesting as a job isolation escape flaw that fundamentally undermines the security boundaries designed to protect system resources. This weakness allows unauthorized access to escalate privileges from a low-privileged user account to the awx user account, which operates with elevated system permissions. The vulnerability is particularly concerning because it enables external attackers to bypass the intended isolation mechanisms that should prevent unauthorized access to sensitive system components and data.
The technical implementation of this flaw stems from inadequate enforcement of job isolation protocols within the ansible-tower framework. When jobs are executed in isolated environments, the system should maintain strict separation between the execution context and the underlying system resources. However, the vulnerability allows attackers to escape these isolation boundaries, effectively breaking down the security controls that separate different user contexts. This represents a critical failure in the principle of least privilege and privilege separation, where the system fails to properly enforce access controls that should prevent unauthorized escalation of privileges.
From an operational impact perspective, this vulnerability creates significant risk to data confidentiality, integrity, and system availability across the affected environment. An attacker who successfully exploits this vulnerability gains access to the awx user account, which typically possesses extensive system privileges and can access sensitive configuration data, credentials, and system resources. The compromise of the awx user account can lead to complete system takeover, data exfiltration, and potential disruption of service availability. The vulnerability's external accessibility means that attackers do not require internal network access or existing credentials to attempt exploitation, making it particularly dangerous in environments with exposed management interfaces.
The security implications of CVE-2021-20253 align with CWE-276, which addresses improper privilege management and inadequate access control mechanisms. This vulnerability also maps to ATT&CK technique T1068, privilege escalation, and T1566, social engineering, as exploitation may involve bypassing security controls through manipulation of job execution processes. Organizations using ansible-tower should immediately implement mitigations including updating to patched versions, reviewing job isolation configurations, and implementing additional network segmentation controls to limit access to management interfaces. The vulnerability highlights the critical importance of maintaining secure default configurations and properly enforcing isolation boundaries in automation platforms that handle sensitive system administration tasks.