ALIASES:

Trojan:Win32/Delf.EP (Microsoft); [0019f2ac.EXE]:Generic Dropper!bcq, [000f80ac.EXE]:Generic Delphi.h (McAfee); Downloader (Symantec); Backdoor.Win32.Hupigon.ieus (Kaspersky); Trojan.Crypt.CFI.Gen (fs) (Sunbelt); Trojan.Generic.2611040 (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: 807,424 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 19 Oct 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.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %User Profile%\NTUSER.DATKwHtA.exe
  • %User Profile%\ntuseroNyKrDtA.exe

(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.)

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Directory\shell\open\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Drive\shell\open\
command

HKEY_CLASSES_ROOT\CLSID\{75EA2845-EAD5-486E-A339-59FED49289A6}

HKEY_CLASSES_ROOT\CLSID\{75EA2845-EAD5-486E-A339-59FED49289A6}\
InprocServer32

HKEY_CLASSES_ROOT\PROTOCOLS\Filter\
text/html

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{75EA2845-EAD5-486E-A339-59FED49289A6}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
PROTOCOLS\Filter\text/html
CLSID = "{75EA2845-EAD5-486E-A339-59FED49289A6}"

Dropping Routine

This backdoor drops the following files:

  • %System%\HoHagmwBg.dll
  • %Program Files%\Common Files\aHoAlXiUk.dll
  • %Program Files%\NetMeeting\netmeetFqGSi.dll.tmp
  • %Windows%\Prefetch\RUNDLL32.EXE-41303AADBiLxEu.dll.tmp

(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.. %Program Files% is the default Program Files folder, usually C:\Program Files.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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

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\Classes\Directory\shell\open
    • command
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Drive\shell\open
    • command
  • In HKEY_CLASSES_ROOT\CLSID
    • {75EA2845-EAD5-486E-A339-59FED49289A6}
  • In HKEY_CLASSES_ROOT\CLSID\{75EA2845-EAD5-486E-A339-59FED49289A6}
    • InprocServer32
  • In HKEY_CLASSES_ROOT\PROTOCOLS\Filter
    • text/html

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\SOFTWARE\Classes\CLSID\{75EA2845-EAD5-486E-A339-59FED49289A6}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\PROTOCOLS\Filter\text/html
    • CLSID = "{75EA2845-EAD5-486E-A339-59FED49289A6}"

Step 4

Search and delete these files

[ 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.
  • %System%\HoHagmwBg.dll
  • %Program Files%\Common Files\aHoAlXiUk.dll
  • %Program Files%\NetMeeting\netmeetFqGSi.dll.tmp
  • %Windows%\Prefetch\RUNDLL32.EXE-41303AADBiLxEu.dll.tmp

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_HUPIGO.ASN. 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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