CVE-2000-0676 in Communicator
Summary
by MITRE
Netscape Communicator and Navigator 4.04 through 4.74 allows remote attackers to read arbitrary files by using a Java applet to open a connection to a URL using the "file", "http", "https", and "ftp" protocols, as demonstrated by Brown Orifice.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability described in CVE-2000-0676 represents a critical security flaw in Netscape Communicator and Navigator web browsers version 4.04 through 4.74 that enables remote attackers to access arbitrary files on a target system. This vulnerability stems from improper validation of URI protocols within the browser's Java applet execution environment, creating a path traversal condition that bypasses normal security boundaries. The flaw specifically affects how the browser handles file protocol connections when invoked through Java applets, allowing malicious code to circumvent local file system restrictions. The vulnerability is particularly dangerous because it leverages the trusted Java applet execution model while exploiting a fundamental flaw in protocol handling that should have prevented such access patterns.
The technical implementation of this vulnerability occurs through the manipulation of Java applet code that establishes connections using the file, http, https, and ftp protocols. When a malicious Java applet executes within the browser context, it can utilize the URLConnection class to open connections to local file paths through the file protocol, effectively bypassing the normal sandbox restrictions that should prevent such access. This flaw falls under CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability demonstrates how a seemingly legitimate feature for accessing different protocol types can be exploited to gain unauthorized access to local system resources, creating a persistent threat vector that remains active as long as vulnerable browser versions are in use.
The operational impact of this vulnerability extends beyond simple file access, as it can enable attackers to read sensitive system files, configuration data, and potentially user information stored locally on the target system. The Brown Orifice demonstration referenced in the vulnerability description shows how attackers can craft specific Java applet code that exploits this flaw to access files that would normally be protected by the operating system's file permissions. This capability allows for reconnaissance activities, data exfiltration, and potential escalation of privileges within the local environment. The vulnerability's impact is particularly severe in enterprise environments where browsers may be used to access both internal and external resources, as it creates a persistent backdoor for attackers to access local files on systems that may not be directly exposed to external network traffic.
Mitigation strategies for CVE-2000-0676 require immediate browser version updates to patched releases that address the protocol validation issue, as well as the implementation of strict network access controls that prevent Java applet execution from accessing local file systems. Organizations should disable Java applet execution entirely when it is not required for business operations, as this eliminates the attack surface entirely. Network segmentation and firewall rules should be implemented to restrict access to local file systems, while application whitelisting policies can prevent execution of untrusted Java applets. The vulnerability highlights the importance of proper input validation and protocol handling in web browsers, and aligns with ATT&CK technique T1059.007 for executing commands through a Java applet, making it a significant concern for security teams implementing defense-in-depth strategies. Additionally, regular security assessments and browser hardening procedures should be implemented to prevent similar vulnerabilities from emerging in other components of the web browser ecosystem, particularly focusing on the secure handling of URI protocols and file system access restrictions.