TROJ_DOWNLOADER.A


 ALIASES:

RDN/Generic Downloader.x!kt (McAfee); Trojan-Banker.Win32.Agent.kld (Kaspersky); Troj/Banloa-WT (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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.

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

467,968 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 Aug 2014

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.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run

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

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLUA = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
ConsentPromptBehaviorAdmin = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
AutoConfigURL = "file://%User Profile%\javau.n"

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

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Connections
DefaultConnectionSettings = "{random values}"

(Note: The default value data of the said registry entry is {random values}.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Connections
SavedLegacySettings = "{random values}"

(Note: The default value data of the said registry entry is {random values}.)

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run
to = "wscript.exe /B %User Profile%\Application Data\WinNtService.vbs"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run
tt = "%User Profile%\addon.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\Application Data\winntservice.vbs
  • %User Temp%\flager
  • %User Profile%\addon.exe
  • %User Profile%\Application Data\temp.txt
  • %User Temp%\4941.tmp
  • %User Profile%\javau.n
  • %User Profile%\Application Data\WinNtService.vbs
  • %User Temp%\t.reg

(Note: %User Profile% is a user's profile folder, where it usually is C:\Documents and Settings\{user name} on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name} on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://o.{BLOCKED}sd0.com/y2.ymp
  • http://o.{BLOCKED}sd0.com/retnc/c.php?tip=[0][CWS07D103][][[P]&inf=
  • {BLOCKED}199.89
  • {BLOCKED}.86.7

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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\CurrentVersion\Policies\Explorer
    • run
  • 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • EnableLUA = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • ConsentPromptBehaviorAdmin = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • AutoConfigURL = "file://%User Profile%\javau.n"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
    • Connection Settings = "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\Connections
    • From: DefaultConnectionSettings = "{random values}"
      To: DefaultConnectionSettings = ""{random values}""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • From: SavedLegacySettings = "{random values}"
      To: SavedLegacySettings = ""{random values}""

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 Profile%\Application Data\winntservice.vbs
  • %User Temp%\flager
  • %User Profile%\addon.exe
  • %User Profile%\Application Data\temp.txt
  • %User Temp%\4941.tmp
  • %User Profile%\javau.n
  • %User Profile%\Application Data\WinNtService.vbs
  • %User Temp%\t.reg

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_DOWNLOADER.A. 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.


Did this description help? Tell us how we did.