TROJ_DLOADER.DNO

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes then deletes itself afterward.

It does not have any propagation routine.

It does not have any backdoor routine.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system and executes them:

• %User Temp%\winlogin.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It executes then deletes itself afterward.

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
winlogin = "%User Temp%\winlogin.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\05F16C88-71D3-42C1-BB4F-E9BAF7DB4A9E

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\05F16C88-71D3-42C1-BB4F-E9BAF7DB4A9E
cfg = "{random}GRGRGRGR}{hostname} "

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan accesses the following websites to download files:

• http://{BLOCKED}4qc2r4bn63.{BLOCKED}b.org:443
• https://{BLOCKED}4qc2r4bn63.{BLOCKED}b.org/gate.php

It saves the files it downloads using the following names:

• %User Temp%\___{random}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

• http://icanhazip.com:443

NOTES:

This Trojan connects to the following URLs to download and install a certificate so it could connect to the malicious site which is in a Tor2web proxy network:

• http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/authrootseq.txt
• http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/authrootstl.cab
• http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/B1BC968BD4F49D622AA89A81F2150152A41D829C.crt

The following registry key would be added after installing the certificate:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SystemCertificates\AuthRoot\Certificates\B1BC968BD4F49D622AA89A81F2150152A41D829C

The following registry entry would be added after installing the certificate:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SystemCertificates\AuthRoot\Certificates\B1BC968BD4F49D622AA89A81F2150152A41D829C
Blob = {hex value}

The following files would be added after installing the certificate:

• %Application Data%\Microsoft\Crypto\RSA\{User's Security Identifier}\{random 1} (Windows Vista and higher versions) - installing certificate
• %Application Data%\Microsoft\Crypto\RSA\{User's Security Identifier}\{random 2} (Windows Vista and higher versions)
• %Application Data%\Microsoft\CryptnetUrlCache\Content\{random 3} (Versions lower than Windows Vista)
• %Application Data%\Microsoft\CryptnetUrlCache\Content\{random 4} (Versions lower than Windows Vista)

It does not have rootkit capabilities.

It does not exploit any vulnerability.