CVE-2002-1849 in Server
Summary
by MITRE
ParaChat Server 4.0 does not log users off if the browser s back button is used, which allows remote attackers to cause a denial of service by repeatedly logging into a chat room, hitting the back button, then logging into the same chat room as a different user, which fills the chat room with invalid users.
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Analysis
by VulDB Data Team • 09/01/2025
The vulnerability described in CVE-2002-1849 represents a significant session management flaw in ParaChat Server 4.0 that fundamentally undermines the system's ability to maintain proper user authentication states. This issue stems from the server's improper handling of browser navigation patterns, specifically when users employ the back button functionality to navigate through chat sessions. The root cause lies in the server's failure to properly invalidate or terminate user sessions when browser navigation occurs, creating a persistent state where multiple user contexts can coexist within the same chat room environment.
The technical implementation of this vulnerability exploits a fundamental weakness in the server's session lifecycle management. When a user accesses a chat room and subsequently uses the browser's back button to return to a previous page, the ParaChat Server fails to recognize this navigation event as a session termination. This oversight allows attackers to repeatedly cycle through the authentication process, creating multiple simultaneous connections to the same chat room while maintaining different user identities. The server's inability to properly track and manage these session transitions results in a buildup of invalid user entries within the chat room, ultimately leading to resource exhaustion and service disruption.
From an operational perspective, this vulnerability creates a straightforward denial of service condition that can be exploited with minimal technical expertise. Attackers can systematically fill chat rooms with invalid user entries by leveraging the back button navigation pattern, effectively consuming server resources and rendering legitimate chat room access impossible for other users. The impact extends beyond simple service disruption as it can compromise the integrity of the chat environment, making it difficult for administrators to maintain proper user access controls and potentially leading to unauthorized access to restricted chat functionalities.
The vulnerability aligns with CWE-613, which addresses inadequate session management, and demonstrates characteristics consistent with ATT&CK technique T1499.004 related to network denial of service attacks. The flaw essentially creates a persistent resource consumption scenario where the server continuously maintains invalid user sessions, leading to memory exhaustion and eventual system instability. This type of vulnerability is particularly dangerous in multi-user environments where chat rooms serve as shared communication platforms, as it can quickly escalate from a minor inconvenience to a complete service outage.
Mitigation strategies should focus on implementing proper session invalidation mechanisms that recognize browser navigation events and terminate stale sessions accordingly. Administrators should consider implementing session timeout mechanisms that are independent of browser navigation patterns, ensuring that user contexts are properly cleaned up when users leave a chat room or when navigation events occur. Additionally, the server should enforce strict user authentication state management that prevents the creation of duplicate or invalid user entries within the same chat room context. Network-level protections such as rate limiting and connection monitoring can also help detect and prevent exploitation attempts, while regular security audits should verify that session management mechanisms properly handle all browser navigation scenarios to prevent similar vulnerabilities from persisting in future deployments.