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TROJ_TRICKBOT.END

August 01, 2017
 Analysis by: Cris Nowell Pantanilla
 ALIASES:

Trojan:Win32/Emotet (Microsoft), Trojan.Win32.Agent.nfaoru (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

181,760 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

27 Jul 2017

Payload:

Connects to URLs/IPs

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.

Installation

This Trojan drops the following copies of itself into the affected system and executes them:

  • %System%\dcomevent.exe
  • %AppLocalData%\Microsoft\Windows\dcomevent.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dcomevent = "%AppLocalData%\Microsoft\Windows\dcomevent.exe"

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • {BLOCKED}.{BLOCKED}.145.224
  • {BLOCKED}.{BLOCKED}.212.79:443
  • {BLOCKED}.{BLOCKED}.50.32
  • {BLOCKED}.{BLOCKED}.175.211
  • {BLOCKED}.{BLOCKED}.38.121
  • {BLOCKED}.{BLOCKED}.192.45
  • {BLOCKED}.{BLOCKED}.107.173
  • {BLOCKED}.{BLOCKED}.245.164:443

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan does the following:

  • It drops the following copy of itself in 64-bit systems:
    • %Windows%\SysWOW64\{string 1}{string 2}.exe
        where {string} is a combination of any of the following strings:
        • agent
        • app
        • audio
        • bio
        • bits
        • cache
        • card
        • cart
        • cert
        • com
        • crypt
        • dcom
        • defrag
        • device
        • dhcp
        • dns
        • event
        • evt
        • flt
        • gdi
        • group
        • help
        • home
        • host
        • info
        • iso
        • launch
        • log
        • logon
        • lookup
        • man
        • math
        • mgmt
        • msi
        • ncb
        • net
        • nv
        • nvidia
        • proc
        • prop
        • prov
        • provider
        • reg
        • rpc
        • screen
        • search
        • sec
        • server
        • service
        • shed
        • shedule
        • spec
        • srv
        • storage
        • svc
        • sys
        • system
        • task
        • time
        • video
        • view
        • win
        • window
        • wlan
        • wmi

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.558.02

FIRST VSAPI PATTERN DATE:

27 Jul 2017

VSAPI OPR PATTERN File:

13.559.00

VSAPI OPR PATTERN Date:

28 Jul 2017

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

Identify and terminate files detected as TROJ_TRICKBOT.END

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dcomevent = "%AppLocalData%\Microsoft\Windows\dcomevent.exe"

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_TRICKBOT.END. 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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