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COMMAND IE Shared codebase of (eg. in Outlook) allows silent delivery and exec of code SYSTEMS AFFECTED Windows current ?? (as of 24 Februrary 2003) PROBLEM http-equiv [http-equiv@excite.com] [http://www.malware.com] posted : Technical silent delivery and installation of an executable no client input other than reading an email or viewing a newsgroup message. Outlook Express 6.00 SP1 Cumulative Pack 1 2 3 4 whatever. This should not be possible. When viewing an email message or a newsgroup message, Outlook Express creates a temp file in the Internet Explorer cache. From here security should be governed by Internet Explorer's security settings. In an html email with internet zone applied, this will not function: <o bject classid="clsi d:1 1 1 1 1 1 1 1-1 1 1 1-1 1 1 1-1 1 1 1" code base="C:WINDOWSFTP.EXE"></object> [screen shot: http://www.malware.com/tsktsk.png 11KB] In an html email message or newsgroup message with internet zone applied this will function: <xml id=oExec> <security><exploit> <![CDATA[ <o bject id="oFile" classid="clsi d:1 1 1 1 1 1 1 1-1 1 1 1-1 1 1 1-1 1 1 1" code base="C:WINDOWSFTP.EXE"></object>]]></exploit></security></xml> <SPAN dataFld=exploit dataFormatAs=html dataSrc=#oExec></SPAN> courtesy of: http://sec.greymagic.com/adv/gm001-ie/ [screen shot: http://www.malware.com/tsktsktsk.png 11KB] NOTE: that default installations of Outlook Express 6.00 are with restricted zone applied. However there still remain many 'happy people' out there that enjoy their html mail messages and html newsgroup messages, and coupling the above with any one of a million other unsolved problems now and in the future with Internet Explorer and Outlook Express, including a new http://www.malware.com/stench.html we are back in business. Notes: This is supposed to be patched: http://microsoft.com/technet/security/bulletin/MS02-015.asp 28 March 2002 -Also- Thor Larholm PivX Solutions [http://www.pivx.com], LLC - Senior Security Researcher explains : The culprit here is the codebase localPath vulnerability which was patched in Internet Explorer by MS02-015 in March 2002. GreyMagic had more fun with this at http://security.greymagic.com/adv/gm001-ie/ which is also the origin of the example displayed. MS02-015 crippled codeBase quite severely in Internet Explorer, completely removing most of its functionality in the Internet Zone. It is still possible to use this vulnerability in Internet Explorer in any local security zone, but getting to that zone in the first place is in itself an obstacle. Whatever Microsoft patched in MS02-015 (crippling codeBase in the Internet Zone to avoid the command execution vulnerability) was only applied to the IE-specific parts of MSHTML and not to any shared parts that thirdparty programs such as Outlook and Outlook Express utilize. This despite our impression that MS02-015 removed the problem. This is apparent if you examine Outlook 2000 which can also execute arbitrary commands automatically upon reading mails if you have set the security zone to the Internet Zone - just like Outlook Express as displayed by http-equiv The default security zone for Outlook 2000 is the Internet Zone. It is first after you apply Office 2000 Service Pack 3 that the default zone is changed to the Restricted zone, so remember either to apply O2KSP3 or manually change your zone settings to Restricted at your earliest convenience. Does Eudora still use the Internet Zone for viewing HTML mail? If so, it is also still vulnerable to the codeBase command execution vulnerability, like any other application that is embedding MSHTML. SOLUTION ?