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TROJ_AGENT.P

May 18, 2013
 ALIASES:

Backdoor:Win32/Agent.Z (Microsoft); BackDoor-CCU.dr (McAfee); Backdoor.Trojan (Symantec); Backdoor.Win32.Agent.p (Kaspersky); BehavesLike.Win32.Malware.mmu (mx-v) (Sunbelt); Trojan horse BackDoor.Agent.T (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:

97,312 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 May 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 registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{B49DA3DF-E569-423d-BDEA-8F89128E8107}

Other System Modifications

This Trojan deletes the following files:

  • %System%\itpapix50.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry keys:

HKEY_CLASSES_ROOT\Html.mm.1

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Html.mm.1\CLSID

HKEY_CLASSES_ROOT\Html.mm

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Html.mm\CLSID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Html.mm\CurVer

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\VersionIndependentProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\Programmable

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\TypeLib

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}\TypeLib

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}\TypeLib
Version = "1.0"

Dropping Routine

This Trojan drops the following files:

  • %System%\msrascfg.ini
  • %System%\mswinapi.dll

(Note: %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

Close all opened browser windows

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_CLASSES_ROOT
    • Html.mm.1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Html.mm.1
    • CLSID
  • In HKEY_CLASSES_ROOT
    • Html.mm
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Html.mm
    • CLSID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Html.mm
    • CurVer
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {B49DA3DF-E569-423d-BDEA-8F89128E8107}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}
    • ProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}
    • VersionIndependentProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}
    • Programmable
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}
    • TypeLib
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {BAF91296-5246-458E-BB13-0E14E64BCD28}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{BAF91296-5246-458E-BB13-0E14E64BCD28}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {608F396B-261D-489D-88C6-86AF5683DC4D}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}
    • TypeLib

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\Classes\CLSID\{B49DA3DF-E569-423d-BDEA-8F89128E8107}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{608F396B-261D-489D-88C6-86AF5683DC4D}\TypeLib
    • Version = "1.0"

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.
  • %System%\msrascfg.ini
  • %System%\mswinapi.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_AGENT.P. 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 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.

  • %System%\itpapix50.dll


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