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TROJ_DL.DA375586

October 24, 2013
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

  TECHNICAL DETAILS

File Size:

212,139 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Oct 2013

Arrival Details

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
teste = "%User Profile%\Application Data\teste.exe"

Other System Modifications

This Trojan modifies the following file(s):

  • %Start Menu%\Programs\Internet Explorer.lnk

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\ftp\UserChoice

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\http\UserChoice

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\https\UserChoice

HKEY_CURRENT_USER\Software\Classes\
ftp\shell\open\
command

HKEY_CURRENT_USER\Software\Classes\
http\shell\open\
command

HKEY_CURRENT_USER\Software\Classes\
https\shell\open\
command

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\ftp\UserChoice
Progid = "ChromeHTML"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\http\UserChoice
Progid = "ChromeHTML"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\Shell\Associations\
UrlAssociations\https\UserChoice
Progid = "ChromeHTML"

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Control Panel
Connection Settings = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
AutoConfigUrl = "ZTTm://mCIk.mCIJBeeBI6AQTBmC7RBeA.RIt"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyHttp1.1 = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
EnableHttp1_1 = "1"

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\VB1.tmp
  • %User Temp%\portatil.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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}3.112.253/sfx.exe
  • http://www.{BLOCKED}asorri.org.br/language/pt-BR/pt-BR.com_banners.txt
  • http://www.{BLOCKED}da.com/modules/mod_sections/tmpl/index.txt

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\ftp
    • UserChoice
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http
    • UserChoice
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\https
    • UserChoice
  • In HKEY_CURRENT_USER\Software\Classes\ftp\shell\open
    • command
  • In HKEY_CURRENT_USER\Software\Classes\http\shell\open
    • command
  • In HKEY_CURRENT_USER\Software\Classes\https\shell\open
    • command
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer
    • Control Panel

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • teste = "%User Profile%\Application Data\teste.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\ftp\UserChoice
    • Progid = "ChromeHTML"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice
    • Progid = "ChromeHTML"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\https\UserChoice
    • Progid = "ChromeHTML"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • Connection Settings = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • AutoConfigUrl = "ZTTm://mCIk.mCIJBeeBI6AQTBmC7RBeA.RIt"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyHttp1.1 = "1"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • From: EnableHttp1_1 = "1"
      To: EnableHttp1_1 = ""1""

Step 6

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\VB1.tmp
  • %User Temp%\portatil.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DL.DA375586. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %Start Menu%\Programs\Internet Explorer.lnk


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