ALIASES:

Trojan.MSIL.Disfa.bdum (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor 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: 295,656 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Jul 2013

Arrival Details

This backdoor 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 backdoor drops the following copies of itself into the affected system:

  • %User Profile%\Volume.exe

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
7a628cda9d1c3f0e85c34e93e172394d = "%User Profile%\Volume.exe .."

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
7a628cda9d1c3f0e85c34e93e172394d = "%User Profile%\Volume.exe .."

Other System Modifications

This backdoor modifies the following file(s):

  • %User Profile%\Application Data\Microsoft

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

It deletes the following files:

  • %User Profile%\MachineKeys\ac4a8043b5a7e6efcb80c0fc7b26b19c_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %User Profile%\S-1-5-21-1645522239-1292428093-682003330-1003\78ba03afadf4fc10e2f500830ac2cf47_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %User Profile%\S-1-5-21-1645522239-1292428093-682003330-1003\e507d84546983e79c7be1ae0d7d95617_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.1980.117984
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.1980.117984
  • %User Profile%\v2.0.50727.42\security.config.cch.1980.118125

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\7a628cda9d1c3f0e85c34e93e172394d

It adds the following registry entries:

HKEY_CURRENT_USER\Software\7a628cda9d1c3f0e85c34e93e172394d
US = "!"

HKEY_CURRENT_USER\Environment
SEE_MASK_NOZONECHECKS = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Volume.exe = "%User Profile%\Volume.exe:*:Enabled:Volume.exe"

Dropping Routine

This backdoor drops the following files:

  • %User Profile%\Microsoft\Crypto
  • %User Profile%\Crypto\RSA
  • %User Profile%\RSA\S-1-5-21-1645522239-1292428093-682003330-1003
  • %User Profile%\RSA\MachineKeys
  • %System Root%\.tmp
  • %User Startup%\7a628cda9d1c3f0e85c34e93e172394d.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

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
    • 7a628cda9d1c3f0e85c34e93e172394d

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
    • 7a628cda9d1c3f0e85c34e93e172394d = "%User Profile%\Volume.exe .."
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 7a628cda9d1c3f0e85c34e93e172394d = "%User Profile%\Volume.exe .."
  • In HKEY_CURRENT_USER\Software\7a628cda9d1c3f0e85c34e93e172394d
    • US = "!"
  • In HKEY_CURRENT_USER\Environment
    • SEE_MASK_NOZONECHECKS = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %User Profile%\Volume.exe = "%User Profile%\Volume.exe:*:Enabled:Volume.exe"

Step 5

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 Profile%\Microsoft\Crypto
  • %User Profile%\Crypto\RSA
  • %User Profile%\RSA\S-1-5-21-1645522239-1292428093-682003330-1003
  • %User Profile%\RSA\MachineKeys
  • %System Root%\.tmp
  • %User Startup%\7a628cda9d1c3f0e85c34e93e172394d.exe

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BLADABIN.QL. 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 7

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.

    • %User Profile%\Application Data\Microsoft

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\MachineKeys\ac4a8043b5a7e6efcb80c0fc7b26b19c_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %User Profile%\S-1-5-21-1645522239-1292428093-682003330-1003\78ba03afadf4fc10e2f500830ac2cf47_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %User Profile%\S-1-5-21-1645522239-1292428093-682003330-1003\e507d84546983e79c7be1ae0d7d95617_6abce574-4afc-42c5-8ab9-5739a84d8a8b
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.1980.117984
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.1980.117984
  • %User Profile%\v2.0.50727.42\security.config.cch.1980.118125


Did this description help? Tell us how we did.