CVE-2018-6608 in Web Browser
Summary
by MITRE
In the WebRTC component in Opera 51.0.2830.55, after visiting a web site that attempts to gather complete client information (such as https://ip.voidsec.com), the browser can disclose a private IP address in a STUN request.
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Analysis
by VulDB Data Team • 06/01/2020
The vulnerability CVE-2018-6608 represents a significant privacy and security flaw within Opera browser's WebRTC implementation that exposes users to potential network enumeration and reconnaissance attacks. This issue specifically affects Opera version 51.0.2830.55 and demonstrates how WebRTC functionality can inadvertently leak private network information even when users believe they are browsing securely. The vulnerability arises from the browser's handling of STUN (Session Traversal Utilities for NAT) requests during WebRTC session establishment, where private IP addresses are transmitted without proper sanitization or network boundary awareness.
The technical flaw stems from Opera's WebRTC component failing to properly filter or mask private IP addresses when constructing STUN requests for network traversal purposes. When users visit malicious websites that attempt to gather comprehensive client information, the browser's WebRTC implementation sends STUN requests containing the user's local network IP addresses, which can include private IP ranges such as 10.x.x.x, 172.16.x.x through 172.31.x.x, and 192.168.x.x. This occurs because the browser does not adequately distinguish between public and private IP addresses during the STUN request construction process, nor does it properly implement network boundary detection mechanisms that should prevent such information leakage.
The operational impact of this vulnerability extends beyond simple privacy concerns to potentially enable sophisticated network reconnaissance attacks. Attackers can leverage this flaw to map internal network topologies, identify network segments, and potentially discover vulnerable internal services that would otherwise remain hidden from external scanning. The vulnerability is particularly concerning because it can be exploited through routine web browsing activities without requiring any special user interaction or explicit malicious software installation. Security researchers have noted that this type of information disclosure can facilitate subsequent attacks such as internal network pivoting, service enumeration, and targeted exploitation of internal systems. The vulnerability aligns with CWE-200 (Information Exposure) and represents a classic example of how network protocols can inadvertently expose sensitive information through improper implementation of privacy controls.
Mitigation strategies for CVE-2018-6608 should focus on both immediate browser updates and network-level controls. Users should immediately update to the latest version of Opera where this vulnerability has been patched, as the fix typically involves implementing proper IP address filtering and ensuring that private IP addresses are not transmitted in STUN requests. Network administrators should also consider implementing firewall rules that block STUN traffic or use network segmentation to limit the exposure of internal IP addresses. The vulnerability demonstrates the importance of implementing proper network boundary detection and IP address sanitization in WebRTC implementations, aligning with ATT&CK technique T1046 (Network Service Scanning) and T1071.1 (Application Layer Protocol: Web Protocols) as attackers can leverage this information to conduct more sophisticated reconnaissance activities. Organizations should also implement monitoring for unusual STUN traffic patterns that might indicate exploitation attempts, as this type of vulnerability often serves as a precursor to more serious attacks in the attack chain.