CVE-2006-0418 in 123 Flash Chat Server
Summary
by MITRE
Eval injection vulnerability in 123 Flash Chat Server 5.0 and 5.1 allows attackers to execute arbitrary code via a crafted username.
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Analysis
by VulDB Data Team • 06/14/2025
The CVE-2006-0418 vulnerability represents a critical server-side evaluation injection flaw discovered in 123 Flash Chat Server versions 5.0 and 5.1. This vulnerability falls under the broader category of code injection attacks and specifically aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" within the Common Weakness Enumeration framework. The flaw resides in the server's handling of user input during the username registration or authentication process, where insufficient sanitization allows maliciously crafted input to be executed as code within the server environment.
The technical implementation of this vulnerability exploits the server's failure to properly validate and sanitize user-provided data before processing it through server-side evaluation mechanisms. Attackers can craft a specially formatted username containing malicious code that gets executed when the server processes the input, potentially allowing full system compromise. This type of vulnerability represents a severe misconfiguration in input validation and output encoding practices, as the system trusts user input without proper sanitization before executing it within the server's operational context.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to gain complete control over the affected server. Successful exploitation can result in unauthorized access to chat logs, user data breaches, and potential use as a pivot point for attacking other systems within the network infrastructure. The vulnerability's severity is amplified by the fact that it requires minimal user interaction to exploit, as simply registering with a malicious username can trigger the code execution. This makes it particularly dangerous in multi-user environments where attackers can leverage the vulnerability to compromise the entire chat server infrastructure.
Security professionals should implement immediate mitigations including input validation and sanitization of all user-provided data, particularly usernames and chat messages. The recommended approach involves applying proper escaping and encoding techniques to prevent malicious code from being interpreted as executable commands. Organizations should also consider implementing network segmentation and monitoring for unusual activity patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of following secure coding practices and adhering to the principle of least privilege when designing server-side applications. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for "Command and Scripting Interpreter: Python" and T1078 for "Valid Accounts" as exploitation typically involves gaining access through legitimate user accounts while executing malicious commands. The incident underscores the necessity of regular security assessments and code reviews to identify and remediate such injection vulnerabilities before they can be exploited by malicious actors.