Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2019-25613 is a denial of service (DoS) vulnerability in Easy Chat Server version 3.1 and earlier. It occurs because the server does not properly verify the source of a communication channel, allowing an attacker to send an excessively large value in the "message" parameter of a POST request. This oversized message causes the application to crash.'}, {'type': 'paragraph', 'content': 'An attacker first establishes a session via the chat.ghp endpoint and then sends a POST request to body2.ghp with a very large message parameter, which triggers the crash remotely without requiring any privileges, user interaction, or authentication.'}] [1]

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Impact Analysis

This vulnerability can cause the Easy Chat Server application to crash, resulting in a denial of service. This means legitimate users will be unable to use the chat service while it is down.

Since the vulnerability can be exploited remotely without authentication or user interaction, an attacker can disrupt the availability of the chat service easily, potentially impacting business operations or user communications.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by attempting to reproduce the exploit steps that cause the Easy Chat Server to crash. Specifically, an attacker or tester can establish a session via the chat.ghp endpoint and then send a POST request to body2.ghp with an excessively large value in the "message" parameter.'}, {'type': 'paragraph', 'content': 'A practical detection method involves sending crafted HTTP requests similar to the proof-of-concept exploit:'}, {'type': 'list_item', 'content': '1. Send an HTTP GET request to /chat.ghp with parameters username=1, password=, room=1, sex=1 to establish a session.'}, {'type': 'list_item', 'content': '2. Send an HTTP POST request to /body2.ghp with form data including a "message" parameter containing a very large string (e.g., 8000 \'A\' characters) to trigger the crash.'}, {'type': 'paragraph', 'content': 'Example commands using curl (assuming the server is running on localhost and port 80):'}, {'type': 'list_item', 'content': 'curl "http://localhost/chat.ghp?username=1&password=&room=1&sex=1"'}, {'type': 'list_item', 'content': 'curl -X POST "http://localhost/body2.ghp" -H "Content-Type: application/x-www-form-urlencoded" -d "message=$(python3 -c \'print("A"*8000)\')&other=params"'}, {'type': 'paragraph', 'content': 'Monitoring the server for crashes or denial of service after these requests indicates the presence of the vulnerability.'}] [1, 2]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'Immediate mitigation steps include preventing attackers from sending oversized data to the vulnerable endpoints and limiting exposure of the Easy Chat Server.'}, {'type': 'list_item', 'content': 'Restrict network access to the Easy Chat Server, allowing only trusted hosts to connect.'}, {'type': 'list_item', 'content': 'Implement input validation or filtering at the network perimeter (e.g., firewall or web application firewall) to block HTTP POST requests with excessively large "message" parameters.'}, {'type': 'list_item', 'content': 'Monitor server logs and system stability to detect and respond quickly to any crash attempts.'}, {'type': 'paragraph', 'content': 'Since the vulnerability is caused by improper verification of input size, applying patches or updates from the vendor when available is the definitive solution.'}] [1]

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