Vulnerability in Apache for Win32 batch file processing - Remote command execution
From: Ory Segal (ORY.SEGAL@SANCTUMINC.COM)Date: 03/21/02
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From: Ory Segal <ORY.SEGAL@SANCTUMINC.COM> To: "'Bugtraq@securityfocus.com'" <Bugtraq@securityfocus.com>, "'vulnwatch@vulnwatch.org'" <vulnwatch@vulnwatch.org>, "'webappsec@securityfocus.com'" <webappsec@securityfocus.com>, "'vuln-dev@securityfocus.com'" <vuln-dev@securityfocus.com>, "'news@securiteam.com'" <news@securiteam.com> Date: Thu, 21 Mar 2002 09:06:46 -0800
Vulnerability in Apache for Win32 batch file processing - Remote command
execution
=> Author: Ory Segal, Sanctum inc. http://www.sanctuminc.com
=> Release date: March, 21st 2002 (Vendor was notified at: Feb. 13th 2002)
=> Vendor: Apache group
=> Product: Apache web server (Win32) - Running DOS batch files
Tested on:
- Apache 1.3.23
- Apache 2.0.28-BETA (By default includes /cgi-bin/test-cgi.bat
file which
enables this attack)
=> Severity: High, remote command execution and arbitrary file viewing.
=> CVE candidate: CAN-2002-0061
(http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-0061)
=> Summary: Because of a the way Apache web server handles DOS batch scripts
it is possible to execute remote commands on the web server by using the
pipe ('|') character.
** IMPORTANT **
The Apache 2.0.x installation is shipped with the default script
/cgi-bin/test-cgi.bat
which can be exploited, but it should be noted that ANY '.bat' or '.cmd'
script
will allow exploitation of this vulnerability.
=> Description: When a request for a DOS batch file (.bat or .cmd) is sent
to an Apache
web server, the server will spawn a shell interpreter (cmd.exe by default)
and
will run the script with the parameters sent to it by the user. Because no
proper validation is done on the input, it is possible to send a pipe
character
('|') with commands appended to it as parameters to the CGI script, and the
shell
interpreter will execute them.
Example:
1)
http://TARGET/cgi-bin/test-cgi.bat?|copy+..\conf\httpd.conf+..\htdocs\httpd.
conf
This request will copy the httpd.conf file residing in the /conf directory
of the Apache
installation, into the virtual web root where it can be viewed by any user.
2) http://TARGET/cgi-bin/test-cgi.bat?|echo+Foobar+>>+..\htdocs\index.html
This will append the string "Foobar" to the index.html file residing in the
virtual
web root directory.
3) http://TARGET/cgi-bin/test-cgi.bat?|dir+c:+>..\htdocs\dir.txt
This will create a file containing the directory listing of the C: drive,
and will put the file in the virtual web root, where any user can read it.
** Notes:
1) Url-Decoding is not provided by Apache except for the '+' character which
is substituted by a space character.
2) Spilling the output into the STDOUT would most likely cause Apache to
write an
error message since it expects the STDOUT of a CGI script to have an HTTP
response format
(potential HTTP headers followed by a mandatory blank line followed by a
response body).
Therefore in order to view the result of a command, it is recommended that
you redirect
the output to a file under the web server's virtual root.
=> Solution: Upgrade your Apache web server to: 1.3.24 (which should be
available later
today), or 2.0.34-beta (which will be published soon). Downloads are located
at:
http://www.apache.org/dist/httpd/
<<apache_advisory.txt>>
Ory Segal
Sanctum, Inc.
http://www.SanctumInc.com/
- text/plain attachment: apache_advisory.txt
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