CVE-2020-10697 in Ansible Tower
Summary
by MITRE • 05/28/2021
A flaw was found in Ansible Tower when running Openshift. Tower runs a memcached, which is accessed via TCP. An attacker can take advantage of writing a playbook polluting this cache, causing a denial of service attack. This attack would not completely stop the service, but in the worst-case scenario, it can reduce the Tower performance, for which memcached is designed. Theoretically, more sophisticated attacks can be performed by manipulating and crafting the cache, as Tower relies on memcached as a place to pull out setting values. Confidential and sensitive data stored in memcached should not be pulled, as this information is encrypted. This flaw affects Ansible Tower versions before 3.6.4, Ansible Tower versions before 3.5.6 and Ansible Tower versions before 3.4.6.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2020-10697 represents a significant security weakness in Ansible Tower's handling of memcached components within OpenShift environments. This flaw stems from insufficient access controls and input validation mechanisms that allow malicious actors to manipulate the memcached service through crafted Ansible playbooks. The vulnerability exists because Tower's memcached instance operates over TCP connections without proper authentication or authorization checks, creating an attack surface where unauthorized parties can inject or modify cached data. The issue is particularly concerning as it leverages the fundamental architecture of Ansible Tower, which relies on memcached for storing and retrieving configuration settings and operational parameters. The flaw affects multiple version streams of Ansible Tower including versions prior to 3.6.4, 3.5.6, and 3.4.6, indicating a widespread impact across the product's release history.
The technical implementation of this vulnerability involves the exploitation of memcached's write operations through Ansible playbook execution. Attackers can craft malicious playbooks that target the memcached service running on the Tower instance, potentially polluting the cache with crafted data. This cache pollution directly impacts the performance and reliability of the Tower service by consuming memory resources and potentially corrupting legitimate cached values. The memcached service, designed for high-performance caching operations, becomes a vector for denial of service when subjected to malicious write operations. The vulnerability's impact extends beyond simple service degradation as it can compromise the integrity of cached configuration data that Tower relies upon for operational functions. According to CWE classification, this vulnerability aligns with CWE-200 (Information Exposure) and CWE-311 (Missing Encryption of Sensitive Data) as it exposes sensitive configuration values that may be stored in the cache and potentially accessible to unauthorized parties. The attack pattern follows ATT&CK technique T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing via Social Engineering) when considering how attackers might gain access to execute malicious playbooks.
The operational impact of CVE-2020-10697 manifests in several ways that can severely compromise the availability and integrity of Ansible Tower deployments. While the attack does not completely terminate the Tower service, it can significantly reduce performance by consuming cache memory and potentially causing cache invalidation cascades that affect system responsiveness. The most concerning aspect involves the potential for data manipulation attacks where attackers can inject malicious values into the cache, leading to incorrect configuration settings being applied to Tower operations. This can result in misconfigured deployments, failed automation tasks, and potentially unauthorized access to systems managed by Tower. The encrypted nature of sensitive data stored in memcached does not prevent the vulnerability, as the issue lies in the cache manipulation rather than the encryption mechanism itself. Organizations using affected Ansible Tower versions face risks including operational disruptions, configuration corruption, and potential escalation of attacks through cache poisoning techniques that could affect downstream systems relying on Tower's configuration data.
Mitigation strategies for CVE-2020-10697 require immediate implementation of network-level security controls and application-level protections. Organizations should implement strict firewall rules that restrict access to memcached TCP ports to only trusted administrative systems and services. The most effective immediate solution involves upgrading to Ansible Tower versions 3.6.4, 3.5.6, or 3.4.6, which contain patches addressing the cache access control vulnerabilities. Network segmentation should be implemented to isolate the memcached service from untrusted networks and limit the attack surface. Additionally, implementing proper authentication mechanisms for memcached access and configuring access control lists can prevent unauthorized write operations. Organizations should also conduct thorough security reviews of their Ansible playbooks to ensure that no malicious code can be executed through legitimate automation workflows. The implementation of monitoring and alerting systems specifically designed to detect unusual memcached activity patterns can provide early warning of potential exploitation attempts. Security teams should consider implementing principle of least privilege access controls for memcached instances and regularly audit cache contents to identify any unauthorized modifications that may have occurred. The vulnerability's resolution through software updates aligns with standard security practices outlined in NIST SP 800-40 and ISO 27001 frameworks for vulnerability management and remediation.