ALIASES:

Trojan.Gen (Symantec); BehavesLike.Win32.Malware.eah (mx-v) (Sunbelt); Trojan.Generic.7077718 (FSecure)

 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: 504,832 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Jan 2012

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
11avisos = "%System Root%\11avisos.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
11desco = "%System Root%\11desco.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Enigma Protector\
29AEB4A0365755F6-B862CAE984EA4D0E

HKEY_CURRENT_USER\Software\Enigma Protector\
29AEB4A0365755F6-B862CAE984EA4D0E\02F01F553A112DCE-00C9DB38C18D5FD1

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Enigma Protector\
29AEB4A0365755F6-B862CAE984EA4D0E\02F01F553A112DCE-00C9DB38C18D5FD1
8BD0F9B1 = "{random values}"

HKEY_CURRENT_USER\Software\Enigma Protector\
29AEB4A0365755F6-B862CAE984EA4D0E
Options = "{random values}"

Dropping Routine

This Trojan drops the following files:

  • %System Root%\11avisos.exe
  • %System Root%\11desco.exe
  • %System Root%\11bbxxbb.exe
  • %System Root%\11cef.exe
  • %System Root%\AVSF0BDFF95BRIAN-D3A1FF858.log

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

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

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_CURRENT_USER\Software\Enigma Protector
    • 29AEB4A0365755F6-B862CAE984EA4D0E
  • In HKEY_CURRENT_USER\Software\Enigma Protector\29AEB4A0365755F6-B862CAE984EA4D0E
    • 02F01F553A112DCE-00C9DB38C18D5FD1

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
    • 11avisos = "%System Root%\11avisos.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 11desco = "%System Root%\11desco.exe"
  • In HKEY_CURRENT_USER\Software\Enigma Protector\29AEB4A0365755F6-B862CAE984EA4D0E\02F01F553A112DCE-00C9DB38C18D5FD1
    • 8BD0F9B1 = "{random values}"
  • In HKEY_CURRENT_USER\Software\Enigma Protector\29AEB4A0365755F6-B862CAE984EA4D0E
    • Options = "{random values}"

Step 5

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 Root%\11avisos.exe
  • %System Root%\11desco.exe
  • %System Root%\11bbxxbb.exe
  • %System Root%\11cef.exe
  • %System Root%\AVSF0BDFF95BRIAN-D3A1FF858.log

Step 6

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