Bugtraq mailing list archives
HTML.dropper
From: "http-equiv () excite com" <http-equiv () excite com>
Date: Wed, 17 Jan 2001 09:09:14 -0800
Internet Explorer 5.5 and accompanying mail and news client afford us the unique ability to dictate which icons and file extensions we require. Specifically, we are able to manufacture an email message to appear as one thing when in fact it is not: 1. What? By carefully calculating a certain length of characters in the subject field of an email message, Outlook Express 5.5 for whatever reason creates an attachment incorporating the text in the body of the message. 2. And We have in fact not attached anything, yet there is a fully functional attachment. Furthermore we can dictate which file association and applicable icon we require in order to execute our file. We can create it to appear as an image file, sound file, html file etc. etc. 3. What does this mean: MIME-Version: 1.0 To: http-equiv () excite com Subject: .hta Content-Type: image/gif; charset=us-ascii Content-Transfer-Encoding: 7bit This will create an email message with no reference to attachments in the headers.This can be particularly troublesome to content filtering gateways and/or security applications that strip attachments through header information that is content disposition: attachment; content-type: application/malware; filename: iloveyou.vbs What the above does is create an attachment, which in this case is an *.hta file, but by manipulating the content-type, it is given an image file icon. We then include in the body of our email message the very simple code to execute whatever we wish, which is automatically incorporated into the manufactured attachment. 4. Working example below. Note: Right-click and save to disk.To be opened in the mail client. Harmless WSH code to execute telnet.exe on the local machine. http://www.malware.com/dropper.eml 5. The possibilities are endless. Any text based executable will suffice. It is also trivial to introduce outside code into the temporary internet folder, where the *.hta is opened. We can draw an executable into the TIF via the image tag (though it numbers), and also by the bgsound tag (which is not numbered). The main problem lies in the fact that we can dictate the icon which has always been a goal of VX community to dupe recipients. Furthermore the fact that there are not legitimate header informations for content filtering and security application screening of attachments etc. is equally problematic. Tested on IE5.5. and OE5.5. win98, fully patched and updated with all so-called service packs. Notes: 1. There is still the security warning with opening the file. However the icon representing the content type should override, most if not all's concern. 2. The actual file extension (*.hta in this case) seems to have to appear in the security warning dialogue box, you can see it at the very end to execute. If the subject length is too long, it creates an odd *.tx file which calls up 'what do you want to open this with [something to this effect]' system requirement. 3. This appears to be somewhat similar to something examined several months ago: http://www.malware.com/yoko.html === Irrelevant Notes: a. We don't mind multi-million dollar security companies cutting and pasting our working examples into test sites to promote their products, you can at least acknowledge who's creation it is. b. We received numerous unsolicited offerings to acquire our domain, ranging from ridiculous quantums of currency to bizarre JV proposals. We will examine for the next several months proposals under both circumstances and should anyone have genuine interest, contact bug () malware com, all communications will be held in the strictest of confidence. Time-wasters will be shown the door however. end call === --- http://www.malware.com | _______________________________________________________ Send a cool gift with your E-Card http://www.bluemountain.com/giftcenter/
Current thread:
- HTML.dropper http-equiv () excite com (Jan 17)
- Re: HTML.dropper Nick FitzGerald (Jan 18)
- <Possible follow-ups>
- Re: HTML.dropper Shane Hird (Jan 19)