Vulnerability Assessment & Network Security Forums
If through a vulnerability assessment, a network security issue is detected for the vulnerability below, applying the appropriate security patches in a timely matter is very important. If you have detected that your system has already been compromised, following CERT's Network Security recovery document will assist with recommended steps for system recovery.
Vulnerability Assessment Details
NIDS evasion options
Detailed Explanation for this Vulnerability Assessment
This test configures Nessus for NIDS evasion (see the 'Prefs' panel).
NIDS evasion options are useful if you want to acertain
the quality of the expensive NIDS you just bought.
HTTP evasion techniques :
- HEAD: use HEAD method instead of GET
- URL encoding:
- Hex: change characters to %XX
- MS UTF-16: change characters to %uXXXX. This works only with IIS.
- UTF-16: change characters to %00%XX. This should *not* work!
- Broken UTF-8: change characters to invalid multibyte UTF8 sequences.
- Absolute URI: insert scheme://host/ in front of the relative URI.
- Double slashes: change every / to //
- Reverse traversal: change / into /dirname/../
'Basic' inserts 8 characters random directory names
'Long' means 1000
character directory name.
- Self-reference: changes every / to /./
- Premature request ending: just like 'reverse traversal', but the directory
name contains %0d%0a (could be translated to CR LF)
- CGI.pm: uses '
' instead of '&' in the query string.
- Parameter hiding: another form of reverse traversal. The directory contains
%3F (could be translated to ?)
- Dos/Windows: uses \ instead of /
- Null method: insert %00 between the method and the URI
- TAB: uses TAB instead of SPACE between the method, the URL and the HTTP
- HTTP/0.9: uses HTTP/0.9 requests (method & URI only, no HTTP version field)
'Premature request ending' and 'Parameter hiding' target 'smart' IDS.
for more information.
Warning: those features are experimental and some
options may result in false negatives!
This test does not do any security check.
Network Security Threat Level: None
Networks Security ID:
Vulnerability Assessment Copyright: This script is Copyright (C) 2002 Michel Arboi / Renaud Deraison
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