TROJ_DROPPE.LK

November 23, 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:

250,880 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

23 Nov 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.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
Port = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
Timeout = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
EnableLogFile = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
LogFilePath = "%System Root%\logfile.txt"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
FilterIp = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
AutoAllow = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
AskUser = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
EnableEventLog = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters
DisableTrayIcon = "{random values}"

Dropping Routine

This Trojan drops the following files:

  • %System Root%\disable.reg
  • %System Root%\disable.bat
  • %System%\AdmDll.dll
  • %System%\r_server.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

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

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_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server
    • Parameters

Step 3

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\SYSTEM\RAdmin\v2.0\Server\Parameters
    • Port = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • Timeout = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • EnableLogFile = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • LogFilePath = "%System Root%\logfile.txt"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • FilterIp = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • AutoAllow = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • AskUser = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • EnableEventLog = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server\Parameters
    • DisableTrayIcon = "{random values}"

Step 4

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.
  • %System Root%\disable.reg
  • %System Root%\disable.bat
  • %System%\AdmDll.dll
  • %System%\r_server.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPE.LK. 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.


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