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TROJ_DROPPER.JAS

October 08, 2012
 Analysis by: Jeffrey Bernardino
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This is the Trend Micro detection for files that exhibit certain behaviors.

  TECHNICAL DETAILS

File Size:

64,512 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

25 Aug 2010

Payload:

Drops files

Installation

This Trojan drops the following files:

  • %System%\Iasex.dll - detected as BKDR_SMALL.LEC
  • %System%\Nwsapagentex.dll - also detected as BKDR_SMALL.LEC

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This is the Trend Micro detection for:

  • Files targeting Trend Micro OSCE server, which are added by TROJ_FAKETM.C to the Trend Micro Scan engine package and are executed with ofcservice service.

It does the following:

  • It injects the dropped .DLL files to the following process:
    • SVCHOST.EXE
  • It registers the dropped .DLL files as a service by creating the following registry entries:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\Nwsapagent\Parameters
    ServiceDll='%System%\Nwsapagentex.dll'

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\Ias\Parameters
    ServiceDll='%System%\Nwsapagentex.dll'

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.439.00

VSAPI OPR PATTERN Date:

05 Sep 2010

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by TROJ_DROPPER.JAS

    • TROJ_FAKETM.C
    • BKDR_SMALL.LEC

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.JAS. 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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