CVE-2016-0899 in RSA Archer eGRC
Summary
by MITRE
EMC RSA Archer GRC 5.5.x before 5.5.3.4 allows remote authenticated users to read the web.config.bak file, and obtain sensitive credential information, by modifying the IIS configuration to set a Content-Type header for .bak files.
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Analysis
by VulDB Data Team • 01/19/2019
The vulnerability identified as CVE-2016-0899 affects EMC RSA Archer GRC version 5.5.x prior to 5.5.3.4, representing a critical information disclosure flaw that enables remote authenticated attackers to access sensitive configuration files. This vulnerability specifically targets the web.config.bak file which contains critical credential information and system configuration parameters that should remain protected from unauthorized access. The flaw stems from improper handling of file extensions within the IIS web server configuration, allowing attackers to manipulate content type headers to bypass normal file access restrictions. The vulnerability falls under CWE-545 which addresses the exposure of sensitive information through improper file access control mechanisms, and aligns with ATT&CK technique T1566.001 for credential access through phishing and T1071.004 for application layer protocol usage. The attack vector requires an authenticated user context, meaning that adversaries must first establish valid credentials before exploiting this weakness, which significantly reduces the attack surface but still represents a serious privilege escalation risk.
The technical implementation of this vulnerability relies on the manipulation of IIS configuration settings to alter how .bak files are served to clients. When the Content-Type header for .bak files is modified to allow direct content delivery rather than forcing download or blocking access, authenticated users can directly access the web.config.bak file through standard HTTP requests. This configuration change effectively removes the default security restrictions that normally prevent direct access to backup configuration files, which typically contain database connection strings, API keys, and other sensitive authentication credentials. The vulnerability demonstrates a classic case of insecure configuration management where default security settings are not properly enforced for backup files, creating an information disclosure window that can be exploited by malicious actors with legitimate access credentials. The flaw represents a failure in the principle of least privilege, where backup files that should be restricted to system administrators are made accessible through simple configuration modifications.
The operational impact of this vulnerability extends beyond simple credential theft, as the web.config.bak file typically contains comprehensive system configuration information that can be leveraged for further attacks. Attackers who successfully exploit this vulnerability can obtain database credentials, encryption keys, and application-specific authentication tokens that may provide access to underlying databases and other connected systems. This information can enable lateral movement within the network, allowing attackers to escalate privileges and access additional resources beyond the initial compromised Archer GRC instance. The vulnerability also poses a risk to compliance and regulatory requirements, as the exposure of configuration files containing sensitive data violates data protection standards and may result in significant penalties. Organizations using this software may face audit failures and security incidents that could compromise their entire security posture, particularly if the compromised credentials provide access to critical business applications and data repositories.
Mitigation strategies for CVE-2016-0899 should focus on both immediate remediation and long-term security hardening measures. The primary solution involves applying the vendor-provided patch or upgrade to EMC RSA Archer GRC 5.5.3.4 or later versions that address this specific configuration vulnerability. Organizations should also implement strict file access controls within IIS configuration to prevent .bak files from being served directly to clients, ensuring that backup files are properly restricted through proper content type handling and access control lists. Security configurations should include disabling automatic content type detection for backup files and implementing proper file permissions that restrict access to system administrators only. Network segmentation and monitoring should be enhanced to detect unusual access patterns to configuration files, while regular security audits should verify that backup files are not accessible through web interfaces. Additionally, organizations should establish robust incident response procedures to quickly detect and respond to unauthorized access attempts, including implementing automated alerts for suspicious file access patterns and maintaining comprehensive logging of all configuration file interactions to support forensic analysis and compliance requirements.