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BKDR_HOSTPOSE.AC

October 13, 2012
 ALIASES:

Backdoor:Win32/Hostposer.B (Microsoft); Downloader.a!c2l (McAfee); Trojan.Gen.2 (Symantec); PAK:UPX, Trojan-Downloader.Win32.VB.awaz (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Gen:Trojan.Heur.bmKfrvOgWmoi2 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This backdoor 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:

22,528 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

14 Jul 2012

Arrival Details

This backdoor 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 backdoor 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\{457C57B8-5A6D-458D-80A2-F6A27914421A}

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Description\
Microsoft\Rpc\UuidTemporaryData

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSQLServer\Client\SuperSocketNetLib\
LastConnect

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}\TypeLib

HKEY_CLASSES_ROOT\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}\InprocServer32

HKEY_CLASSES_ROOT\BrowserHelper.CBrowserHelper

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Description\
Microsoft\Rpc\UuidTemporaryData
NetworkAddress = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Description\
Microsoft\Rpc\UuidTemporaryData
NetworkAddressLocal = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSQLServer\Client\SuperSocketNetLib\
LastConnect
cacortex.db.7172228.hostedresource.com = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}\TypeLib
Version = "1.0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
ProgID = "BrowserHelper.CBrowserHelper"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
TypeLib = "{B36032E1-C64C-422F-95CB-347AC027C807}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
VERSION = "1.0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
BrowserHelper.CBrowserHelper
Clsid = "{457C57B8-5A6D-458D-80A2-F6A27914421A}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
ProxyStubClsid = "{00020424-0000-0000-C000-000000000046}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
ProxyStubClsid32 = "{00020424-0000-0000-C000-000000000046}"

Dropping Routine

This backdoor drops the following files:

  • %User Profile%\Application Data\mozsqlit.dll

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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_LOCAL_MACHINE\Software\Description\Microsoft\Rpc
    • UuidTemporaryData
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\SuperSocketNetLib
    • LastConnect
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {B36032E1-C64C-422F-95CB-347AC027C807}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{B36032E1-C64C-422F-95CB-347AC027C807}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {953DC57F-5A20-467E-9C9E-D9631783CE0B}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
    • TypeLib
  • In HKEY_CLASSES_ROOT\CLSID
    • {457C57B8-5A6D-458D-80A2-F6A27914421A}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
    • InprocServer32
  • In HKEY_CLASSES_ROOT
    • BrowserHelper.CBrowserHelper

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\Description\Microsoft\Rpc\UuidTemporaryData
    • NetworkAddress = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Description\Microsoft\Rpc\UuidTemporaryData
    • NetworkAddressLocal = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\SuperSocketNetLib\LastConnect
    • cacortex.db.7172228.hostedresource.com = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}\TypeLib
    • Version = "1.0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
    • ProgID = "BrowserHelper.CBrowserHelper"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
    • TypeLib = "{B36032E1-C64C-422F-95CB-347AC027C807}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{457C57B8-5A6D-458D-80A2-F6A27914421A}
    • VERSION = "1.0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\BrowserHelper.CBrowserHelper
    • Clsid = "{457C57B8-5A6D-458D-80A2-F6A27914421A}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
    • ProxyStubClsid = "{00020424-0000-0000-C000-000000000046}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{953DC57F-5A20-467E-9C9E-D9631783CE0B}
    • ProxyStubClsid32 = "{00020424-0000-0000-C000-000000000046}"

Step 5

Search and delete this file

[ Learn More ]
There may be some component files 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\mozsqlit.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_HOSTPOSE.AC. 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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