CVE-1999-0378 is a medium-severity vulnerability affecting Trend Micro's InterScan VirusWall product running on Solaris systems. The vulnerability arises because the InterScan VirusWall fails to scan files for viruses when a single HTTP request contains two GET commands. Normally, InterScan VirusWall acts as a gateway antivirus scanner, inspecting HTTP traffic to detect and block malicious content before it reaches the internal network or end users. However, this specific malformed HTTP request with multiple GET commands bypasses the scanning mechanism, allowing potentially infected files to pass through uninspected. The vulnerability does not require authentication and can be exploited remotely over the network, as it targets the HTTP traffic handled by the product. The CVSS score of 5.0 (medium) reflects that the vulnerability impacts confidentiality by allowing malicious files to evade detection, but it does not directly affect integrity or availability. The attack complexity is low, and no user interaction is needed. Since the vulnerability was published in 1999 and no patch is available, it likely affects legacy systems still running this product version on Solaris. No known exploits have been reported in the wild, but the vulnerability remains a risk if such outdated systems are exposed to untrusted HTTP traffic.

For European organizations, the primary impact is the increased risk of malware infection due to the bypass of antivirus scanning on HTTP traffic. Organizations relying on InterScan VirusWall on Solaris platforms as a security layer could unknowingly allow malicious files to enter their networks, potentially leading to data breaches or further compromise. This is particularly concerning for industries with strict data protection requirements such as finance, healthcare, and government sectors in Europe. The confidentiality of sensitive data could be compromised if malware exploits this bypass to deliver payloads or exfiltrate information. Although the vulnerability does not directly affect system integrity or availability, the indirect consequences of malware infections could be severe, including ransomware attacks or persistent threats. Given the age of the vulnerability and lack of patches, the risk is mostly relevant to legacy systems that have not been updated or replaced, which may still exist in some European organizations with Solaris infrastructure.

Since no patch is available for this vulnerability, European organizations should consider the following specific mitigations: 1) Identify and inventory all systems running InterScan VirusWall on Solaris to assess exposure. 2) Immediately isolate or decommission legacy Solaris systems running this product if possible, replacing them with supported and updated security solutions. 3) Implement network-level protections such as web application firewalls (WAFs) or intrusion prevention systems (IPS) that can detect and block malformed HTTP requests containing multiple GET commands to prevent exploitation. 4) Employ strict network segmentation to limit exposure of vulnerable systems to untrusted networks, especially the internet. 5) Monitor HTTP traffic logs for suspicious patterns indicative of attempts to exploit this vulnerability. 6) Educate security teams about this legacy vulnerability to ensure awareness during incident response. 7) Consider deploying additional endpoint detection and response (EDR) tools to detect malware that might bypass the antivirus scanning layer. These targeted mitigations go beyond generic advice by focusing on compensating controls and legacy system management.