Modified By:: Joshua Paul Ignacio

 

Trojan.Win64.Agentb.dm (KASPERSKY), W64/Agent.GK!tr (FORTINET)

 PLATFORM:

Windows

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Backdoor

  • Destructiveness:
    No

  • Encrypted:
    No

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Downloaded from the Internet

This is the Trend Micro detection for the backdoor installed by the PowerTrick post-exploitation toolkit believed to be developed by creators of Trickbot.

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.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File size: 215,040 bytes
File type: , EXE
Memory resident: Yes
INITIAL SAMPLES RECEIVED DATE: 15 October 2019
PAYLOAD: Connects to URLs/IPs

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 and executes the following files:

  • {Malware Path}\{Malware Name}.exe:$FILE → contains {Malware Path}\{Malware Name}.exe
  • {Malware Path}\{Malware Name}.exe:$GUID → contains /anchor_dns/{Workstation Name}_{Windows Version}.<{32-character long client ID}>/[0-1]/{Content}\xb[0-9]
  • {Malware Path}\{Malware Name}.exe:$TASK → contains "{string1} autoupdate#{5 Random Numbers}.xml"
    • {string1} can be any of the folders found on %Application Data%
  • "{string1} autoupdate#{5 Random Numbers}".xml → a task scheduler that executes the malware sample with parameter -u every fifteenth minute

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Backdoor connects to the following website to send and receive information:

  • {Obfuscated Message Type + UUID}{Content}.{BLOCKED}ivo.com
    • where Message Type can be any of the following:
      • Type 0 (Sending of Data)
      • Type 1 (Preparation for receival of Data)
      • Type 2 (Receiving of Data)

It adds the following scheduled tasks:

  • Task Name: {string1} autoupdate#{5 Random Numbers}
  • Trigger: At log on of any user; At 8:38PM every day for every 15 minutes for a duration of 1 day. Both trigger expires at 12/31/2028 11:59:59PM
  • Action: Starts a program → %User Temp%\{Malware Name}.exe -u
    • -u will perform standard communication with C2 server using subdomain names to send data and resolved IPs as receival of data

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 15.618.04
First VSAPI Pattern Release Date: 14 October 2019
VSAPI OPR PATTERN-VERSION: 15.619.00
VSAPI OPR PATTERN DATE: 15 October 2019

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ learnMore ]

Step 4

Search and delete this file

[ learnMore ]
There may be some 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 Temp%\{Malware Name}.exe
  • {Malware Path}\{Malware Name}\{Malware Name}:$FILE
  • {Malware Path}\{Malware Name}\{Malware Name}:$GUID
  • {Malware Path}\{Malware Name}\{Malware Name}:$TASK
  • "{string1} autoupdate#{5 Random Numbers}".xml

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win64.ANCHOR.A. 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.

Step 6

  1. Open a command prompt.
    • For Windows 7 users, click Start, enter CMD in the Find input field, and press Enter.
  2. In the CMD console, enter the following:

    ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [+I | -I] [drive:][path][filename] [/S [/D] [/L]]

    Where:
    + Activates an attribute
    - Disables an attribute
    R Read-only file attribute
    A Archive file attribute
    S System file attribute
    H Hidden file attribute
    I Indexed file attribute without content
    [drive:][path][filename]
    Specifies one or more files in the current folder and all its subfolders
    /S Processes the corresponding files in the current folder and all its subfolders
    /D Process folders
    /L Act on the attributes of the symbolic link instrad of the target of the symbolic link
    Example:
    To make all files and folders (including subfolders visible in drive D:
    ATTRIB –H D:\* /S /D
  3. Repeat the step above for folders and files from other drives or directories.


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