CVE-2018-4030 in Smart Firewall
Summary
by MITRE
An exploitable vulnerability exists the safe browsing function of the CUJO Smart Firewall, version 7003. The bug lies in the way the safe browsing function parses HTTP requests. The "Host" header is incorrectly extracted from captured HTTP requests, which would allow an attacker to visit any malicious websites and bypass the firewall. An attacker could send an HTTP request to exploit this vulnerability.
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Analysis
by VulDB Data Team • 08/03/2023
The CVE-2018-4030 vulnerability represents a critical security flaw in the CUJO Smart Firewall's safe browsing functionality, specifically targeting version 7003 which was widely deployed in home and small office networks. This vulnerability resides within the firewall's HTTP request processing mechanism, where the system fails to properly validate and extract the Host header from incoming HTTP traffic. The flaw demonstrates a classic example of improper input validation and header parsing, creating a pathway for malicious actors to circumvent network security measures that are meant to protect users from harmful web content. The vulnerability's exploitation potential is particularly concerning given that CUJO firewalls are designed to provide comprehensive network protection, making this a significant weakness in the security infrastructure of numerous households and small businesses.
The technical implementation of this vulnerability stems from the flawed parsing logic within the firewall's safe browsing module. When HTTP requests pass through the device, the system incorrectly handles the Host header extraction process, allowing attackers to manipulate or inject malicious content that bypasses the intended security checks. This parsing error creates a condition where the firewall's threat detection mechanisms fail to properly analyze the destination of HTTP requests, essentially rendering the safe browsing feature ineffective. The vulnerability's classification aligns with CWE-20, which describes improper input validation, and CWE-22, addressing path traversal issues that can occur when system components fail to properly sanitize user-supplied data. The attack vector is straightforward - an attacker can craft specially formatted HTTP requests that exploit the header parsing flaw to access blocked or malicious websites without triggering the firewall's security alerts.
The operational impact of CVE-2018-4030 extends beyond simple bypass of firewall rules, creating a comprehensive security risk for networks protected by CUJO devices. Organizations and individuals relying on this firewall for protection against malware, phishing, and other web-based threats face significant exposure, as the vulnerability allows for complete circumvention of the device's intended security functions. Network administrators may remain unaware of ongoing malicious activity, as the firewall fails to log or block access to harmful sites that would normally be flagged. This vulnerability particularly affects the firewall's ability to enforce web content filtering policies, potentially exposing users to drive-by downloads, credential harvesting, and other sophisticated attacks that rely on bypassing traditional network security controls. The attack surface is further expanded by the fact that this vulnerability can be exploited remotely without requiring physical access or advanced technical skills, making it particularly dangerous in environments where network security is paramount.
Mitigation strategies for CVE-2018-4030 should focus on immediate firmware updates from the vendor, as this vulnerability was addressed through patches that corrected the HTTP header parsing logic. Network administrators should implement additional monitoring measures to detect anomalous traffic patterns that might indicate exploitation attempts, particularly focusing on unusual Host header values or malformed HTTP requests. The implementation of network segmentation and additional security layers, such as proxy servers with proper header validation, can provide defense-in-depth measures while waiting for official patches. Organizations should also consider conducting comprehensive security audits of their network infrastructure to identify other potential vulnerabilities in similar devices or systems that might exhibit similar parsing or validation flaws. From an ATT&CK framework perspective, this vulnerability maps to techniques involving evasion of security controls and command and control communication, highlighting the need for layered security approaches that don't rely solely on a single point of failure. The vulnerability serves as a reminder of the critical importance of proper input validation and the potential consequences when security-critical components fail to properly sanitize network traffic data.