CVE-2008-7161 in FortiOS
Summary
by MITRE
Fortinet FortiGuard Fortinet FortiGate-1000 3.00 build 040075,070111 allows remote attackers to bypass URL filtering via fragmented GET or POST requests that use HTTP/1.0 without the Host header. NOTE: this issue might be related to CVE-2005-3058.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability described in CVE-2008-7161 affects Fortinet FortiGate-1000 firewall appliances running FortiGuard software version 3.00 build 040075,070111. This security flaw represents a significant bypass of the device's URL filtering capabilities, which are designed to prevent unauthorized access to specific web resources. The vulnerability specifically targets the HTTP protocol handling mechanisms within the firewall's content inspection system, creating a potential pathway for malicious actors to circumvent security controls that should block access to harmful or inappropriate websites.
The technical implementation of this vulnerability stems from how the FortiGate appliance processes fragmented HTTP requests that utilize HTTP/1.0 protocol without the mandatory Host header field. When HTTP/1.0 requests are sent without the Host header, the firewall's URL filtering logic fails to properly parse and inspect the complete request, allowing attackers to craft malicious requests that appear to be legitimate but contain hidden or malformed components. This flaw exploits a gap in the HTTP protocol handling where the absence of the Host header in HTTP/1.0 requests creates a parsing ambiguity that the firewall's filtering engine cannot adequately resolve.
The operational impact of this vulnerability is substantial as it enables remote attackers to bypass the firewall's web content filtering policies without requiring authentication or physical access to the device. Attackers can leverage this weakness to access blocked websites, potentially gaining access to malware distribution sites, phishing pages, or other malicious resources that should be restricted by the organization's security policies. This bypass capability undermines the fundamental security posture of organizations relying on FortiGate appliances for web filtering, potentially leading to data breaches, malware infections, or other security incidents that could compromise network integrity and confidentiality.
Organizations affected by this vulnerability should implement immediate mitigations including updating to the latest firmware versions that address the HTTP parsing issue, configuring the firewall to enforce strict HTTP/1.1 protocol compliance, and implementing additional network monitoring to detect anomalous HTTP traffic patterns. The vulnerability aligns with CWE-444, which describes improper handling of HTTP requests, and represents a variant of the broader class of issues related to HTTP protocol implementation flaws. From an ATT&CK framework perspective, this vulnerability maps to techniques involving protocol manipulation and evasion of network defenses, specifically targeting the network egress filtering and web proxy capabilities that organizations rely upon for security enforcement. The issue may also be related to CVE-2005-3058, indicating a potential pattern of HTTP parsing vulnerabilities in Fortinet's products that require comprehensive security assessments and remediation efforts across affected deployments.