1. Introduction
WebServer 4 Everyone Host Field Header Buffer Overflow is a vulnerability where the web server crashes when processing requests with long filenames and a specific Host header (‘127.0.0.1’). This can lead to denial of service, disrupting website availability. Systems running vulnerable versions of WebServer 4 Everyone are affected. Impact on confidentiality is unlikely but integrity and availability may be compromised.
2. Technical Explanation
The vulnerability occurs due to insufficient input validation when handling the Host request header combined with a long filename in the URL. This allows an attacker to send a crafted HTTP request that overflows a buffer, causing the server to crash. The CVE identifier for this issue is CVE-2002-1941. An example attack involves sending a GET request with a filename exceeding 2000 bytes and setting the Host header to ‘127.0.0.1’. Affected versions are those of WebServer 4 Everyone that do not include appropriate buffer size checks.
- Root cause: Lack of proper bounds checking on the length of the Host request header when combined with a long filename.
- Exploit mechanism: An attacker sends an HTTP GET request containing a long filename (over 2000 bytes) and sets the Host header to ‘127.0.0.1’. This triggers the buffer overflow, leading to a server crash.
- Scope: WebServer 4 Everyone versions prior to any patch addressing CVE-2002-1941 are affected.
3. Detection and Assessment
Confirming vulnerability requires checking the version of WebServer 4 Everyone running on a system, and testing with a crafted request. A quick check involves identifying the server software via HTTP headers. More thorough assessment uses specific exploit attempts.
- Quick checks: Use `curl -I
` to inspect the Server header in the response. - Scanning: Nessus plugin ID 20384 may detect this vulnerability, but results should be verified manually.
- Logs and evidence: Check web server logs for crashes or errors related to buffer overflows when processing requests with long filenames. Look for entries indicating a failure during Host header parsing.
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