CVE-2018-9195 in FortiOS
Summary
by MITRE
Use of a hardcoded cryptographic key in the FortiGuard services communication protocol may allow a Man in the middle with knowledge of the key to eavesdrop on and modify information (URL/SPAM services in FortiOS 5.6, and URL/SPAM/AV services in FortiOS 6.0.; URL rating in FortiClient) sent and received from Fortiguard severs by decrypting these messages.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability described in CVE-2018-9195 represents a critical cryptographic weakness in Fortinet's FortiGuard services communication protocol that affects multiple versions of FortiOS and FortiClient software. This issue stems from the implementation of a hardcoded cryptographic key within the communication framework that governs how devices interact with FortiGuard servers for various security services including URL filtering, spam protection, and antivirus scanning. The presence of such a static key fundamentally undermines the security assurances typically provided by cryptographic protocols, creating a significant attack surface for malicious actors who can exploit this weakness to compromise the integrity and confidentiality of network communications.
The technical flaw manifests as a violation of fundamental cryptographic principles where a predetermined key value is embedded within the software code rather than being dynamically generated or securely managed through proper key distribution mechanisms. This hardcoded key serves as the cornerstone for encrypting and decrypting messages between FortiOS devices and FortiGuard servers, making it possible for an attacker who gains knowledge of this key to perform man-in-the-middle attacks with minimal detection risk. The vulnerability affects both FortiOS 5.6 and 6.0 versions, with specific impact on URL/SPAM services in version 5.6 and URL/SPAM/AV services in version 6.0, along with URL rating functionality in FortiClient implementations, indicating a widespread exposure across multiple security service categories within Fortinet's ecosystem.
The operational impact of this vulnerability extends far beyond simple data interception, as it enables attackers to not only eavesdrop on sensitive communications but also to actively modify the content being transmitted between network devices and FortiGuard services. This dual capability of passive monitoring and active manipulation creates a dangerous scenario where threat actors can alter security policies, redirect users to malicious websites, or inject false security alerts that could lead to confusion and potential compromise of the entire network security posture. The implications are particularly severe given that these services are fundamental to network security operations, meaning that an attacker with access to the hardcoded key could effectively undermine the security controls that organizations rely upon to protect their networks from various threats including malware, phishing attacks, and unauthorized access attempts.
Organizations affected by this vulnerability should immediately implement mitigations that include replacing the hardcoded cryptographic key with a dynamically generated secure key, updating to patched versions of FortiOS and FortiClient software, and implementing network monitoring to detect any anomalous communications that might indicate exploitation attempts. The remediation process should also involve conducting comprehensive security assessments to identify any potential compromise that may have occurred during the period when the vulnerable systems were operational. This vulnerability aligns with CWE-327 which addresses the use of weak cryptographic algorithms and hardcoded keys, and represents a clear violation of the principle of least privilege and secure key management practices that are fundamental to maintaining cryptographic security. From an ATT&CK perspective, this vulnerability maps to techniques involving credential access and defense evasion, as attackers could use this weakness to establish persistent access to network security controls while remaining undetected by traditional monitoring systems that would not expect to see encrypted traffic being decrypted through a hardcoded key mechanism.