CVE-2017-7528 in CloudForms Management Engine
Summary
by MITRE
Ansible Tower as shipped with Red Hat CloudForms Management Engine 5 is vulnerable to CRLF Injection. It was found that X-Forwarded-For header allows internal servers to deploy other systems (using callback).
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Analysis
by VulDB Data Team • 05/04/2023
The vulnerability identified as CVE-2017-7528 represents a critical CRLF (Carriage Return Line Feed) injection flaw within Ansible Tower version 3.1.3 that ships with Red Hat CloudForms Management Engine 5. This vulnerability stems from improper input validation in the handling of HTTP headers, specifically the X-Forwarded-For header which is commonly used in web applications to identify the original IP address of a client connecting through an HTTP proxy or load balancer. The flaw allows malicious actors to inject CRLF sequences into HTTP headers, potentially enabling them to manipulate HTTP responses and bypass security controls.
The technical implementation of this vulnerability occurs when the Ansible Tower application processes the X-Forwarded-For header without adequate sanitization of user-supplied input. When an attacker can control or influence this header value, they can inject CRLF sequences that create additional HTTP headers or manipulate existing ones. This manipulation can be leveraged to perform various malicious activities including HTTP response splitting, cache poisoning, and potentially unauthorized access to internal systems. The vulnerability is particularly dangerous because it enables attackers to deploy callback mechanisms that can be used to execute arbitrary commands on internal systems that are otherwise protected by network segmentation.
The operational impact of CVE-2017-7528 extends beyond simple header manipulation as it creates a pathway for attackers to escalate privileges and gain unauthorized access to internal infrastructure. The vulnerability allows threat actors to exploit the callback functionality within Ansible Tower to establish communication channels with internal systems, potentially enabling them to execute arbitrary code, exfiltrate data, or establish persistent access points within the network. This represents a significant risk to organizations that rely on Ansible Tower for automation and configuration management, as it can lead to complete compromise of the automation infrastructure and potentially broader network access.
Security practitioners should consider this vulnerability in the context of CWE-113 which specifically addresses improper neutralization of CRLF characters in HTTP headers. The attack surface aligns with techniques described in the MITRE ATT&CK framework under the T1071.004 sub-technique for application layer protocol: web protocols, and potentially T1059 for command and script injection. Organizations should implement immediate mitigations including input validation for all HTTP headers, particularly those used in proxy configurations, and consider deploying web application firewalls to detect and block malicious CRLF sequences. The vulnerability also highlights the importance of proper header sanitization in web applications and demonstrates how seemingly benign header processing can create significant security risks when not properly validated against injection attacks.