TROJ_DELF.CVT


 ALIASES:

ERROR (Microsoft); RDN/Downloader.a!jv (McAfee); Infostealer.Gamania (Symantec); Trojan-Dropper.Win32.Delf.ze (Kaspersky); Packed.Win32.Upack (v) (Sunbelt); Trojan horse Dropper.Generic.GSL (AVG)

 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:

571,710 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Jul 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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
NTdhcp = "%System%\NTdhcp.exe"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\navapsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\RsRavMon

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\RsCCenter

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\kavsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KVSrvXP

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KVWSC

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KPfwSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KWatchSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SNDSrvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ccProxy

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ccEvtMgr

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ccSetMgr

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SPBBCSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Symantec Core LC

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NPFMntor

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MskService

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\FireSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\McShield

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\McTaskManager

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\McAfeeFramework

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\RfwService

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\navapsvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\RsRavMon
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\RsCCenter
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\kavsvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KVSrvXP
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KVWSC
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KPfwSvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KWatchSvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SNDSrvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ccProxy
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ccEvtMgr
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ccSetMgr
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SPBBCSvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Symantec Core LC
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\NPFMntor
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\MskService
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\FireSvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\McShield
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\McTaskManager
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\McAfeeFramework
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\RfwService
Start = "4"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = "no"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wscsvc
Start = "4"

(Note: The default value data of the said registry entry is 2.)

HKEY_CURRENT_USER\Software\Microsoft\
Internet Connection Wizard
Completed = "{random values}"

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

Dropping Routine

This Trojan drops the following files:

  • %System Root%\xiaoma.exe
  • %System Root%\Setup.exe
  • %Windows%\Deleteme.bat
  • %Windows%\uninstal.bat
  • %Windows%\svchost.DLL
  • %Windows%\svchostKey.DLL
  • %System%\KvNative.bak
  • %System%\NTdHcP.exe
  • %Windows%\svchost.exe

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://mitaoxiang.{BLOCKED}y.myrice.com/ip.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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • navapsvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • RsRavMon
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • RsCCenter
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • kavsvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • KVSrvXP
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • KVWSC
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • KPfwSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • KWatchSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • SNDSrvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • ccProxy
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • ccEvtMgr
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • ccSetMgr
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • SPBBCSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Symantec Core LC
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • NPFMntor
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • MskService
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • FireSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • McShield
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • McTaskManager
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • McAfeeFramework
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • RfwService

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\Run
    • NTdhcp = "%System%\NTdhcp.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\navapsvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\RsRavMon
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\RsCCenter
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\kavsvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KVSrvXP
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KVWSC
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KPfwSvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KWatchSvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SNDSrvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\ccProxy
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\ccEvtMgr
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\ccSetMgr
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SPBBCSvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Symantec Core LC
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NPFMntor
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\MskService
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\FireSvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\McShield
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\McTaskManager
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\McAfeeFramework
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\RfwService
    • Start = "4"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Check_Associations = "no"

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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wscsvc
    • From: Start = "4"
      To: Start = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Connection Wizard
    • From: Completed = "{random values}"
      To: Completed = ""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.
  • %System Root%\xiaoma.exe
  • %System Root%\Setup.exe
  • %Windows%\Deleteme.bat
  • %Windows%\uninstal.bat
  • %Windows%\svchost.DLL
  • %Windows%\svchostKey.DLL
  • %System%\KvNative.bak
  • %System%\NTdHcP.exe
  • %Windows%\svchost.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DELF.CVT. 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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