Snort mailing list archives

Re: The content pattern of Rule SID: 19713 can be improved


From: Ruowen Wang <rwang9 () ncsu edu>
Date: Mon, 29 Jul 2013 08:41:48 -0700

Hi Alex,

Thanks for pointing this out. Actually, I was previously checking an old
snortrules-2922, which didn't contain the 24187, 24188 rules. I check the
latest one snortrules-2946. I find that 24188 can cover Metasploit attack.

It's good to know public exploits are covered by Snort rules. I also notice
there is a specific rule file exploit-kit.rules focusing on exploit tool
kits. That's great!

Thanks again!

Thank you very much! Have a nice day!
----
Looking forward to your reply

Best Regards!
Sincerely yours,

*Ruowen Wang*
**Graduate Student
Department of Computer Science
North Carolina State University
E-mail: rwang9 () ncsu edu



On Mon, Jul 29, 2013 at 7:06 AM, Alex McDonnell
<amcdonnell () sourcefire com>wrote:

Hi Ruowen,

If you search through the ruleset for the CVE 2011-2371 you will find that
there are more rules that cover this vulnerability, on top of 19713 there
is 19714, 24187 and 24188. Each of these rules covers different vectors and
the should cover all public exploits.

thanks,
Alex McDonnell
VRT


On Mon, Jul 29, 2013 at 1:42 AM, Ruowen Wang <rwang9 () ncsu edu> wrote:

Dear All,

I am doing a research to test Snort rules using Metasploit exploit
scripts. I find that the content pattern of the rule sid:19713 might be
inaccurate and can be improved. The rule is:

alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any
(msg:"BROWSER-FIREFOX Mozilla Array.reduceRight integer overflow";
flow:to_client,established; file_data; content:"a.length=0xffffffff";
nocase; content:"a.reduceRight|28|callback|2C|0|29|"; distance:0; nocase;
metadata:policy balanced-ips drop, policy security-ips drop, service http;
reference:bugtraq,48372; reference:cve,2011-2371; classtype:attempted-user;
sid:19713; rev:2;)

I find that in its content patterns "a.length..." and "a.reduce...", "a"
is actually a JavaScript var name (more specifically, it is an Array object
in this attack), which can be freely chosen by attacker. In addition, I
find this rule cannot detect the Metasploit attack. The corresponding
exploit is

http://dev.metasploit.com/redmine/projects/framework/repository/entry/modules/exploits/windows/browser/mozilla_reduceright.rb

If there is anyone who is familiar with this rule, please take a look,
and correct me if I am wrong.

Thank you very much! Have a nice day!


Best Regards!
Ruowen




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