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BKDR_ZEGOST.NFU

May 23, 2014
 ALIASES:

Backdoor:Win32/Zegost.AD (Microsoft); RDN/Generic BackDoor!xy (McAfee); HEUR:Trojan.Win32.Generic (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse BackDoor.Generic_r.GCH (AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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:

274,886 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

13 May 2014

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:

  • %Windows%\nannaa.exe

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

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Pqrstu Wxyabcde Ghi
Description = "Pqrstuvw Yabcdefgh Jklmnop Rstuvwxy Bcd"

Dropping Routine

This backdoor drops the following files:

  • vir0.exe
  • vir1.exe
  • vir2.exe
  • vir3.exe
  • vir4.exe
  • vir5.exe
  • vir6.exe
  • vir7.exe
  • vir8.exe
  • vir9.exe

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}0.1

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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

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\SYSTEM\ControlSet001\Services\Pqrstu Wxyabcde Ghi
    • Description = "Pqrstuvw Yabcdefgh Jklmnop Rstuvwxy Bcd"

Step 3

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.
  • vir0.exe
  • vir1.exe
  • vir2.exe
  • vir3.exe
  • vir4.exe
  • vir5.exe
  • vir6.exe
  • vir7.exe
  • vir8.exe
  • vir9.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZEGOST.NFU. 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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