Author: Robert Nicole Malagad   

 

Trojan:Win32/Casdet!rfn (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type:
    Trojan

  • Destructiveness:
    No

  • Encrypted:
    Yes

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Dropped by other malware, Downloaded from the Internet

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 connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File size: 987,500 bytes
File type: EXE
Memory resident: No
INITIAL SAMPLES RECEIVED DATE: 17 September 2018
PAYLOAD: Downloads files

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 adds the following folders:

  • %AppDataLocal%\chrome

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It drops the following component file(s):

  • %AppDataLocal%\chrome.crx
  • %AppDataLocal%\chrome\content.js
  • %AppDataLocal%\chrome\manifest.json
  • %AppDataLocal%\chrome\page.js
  • %AppDataLocal%\chrome\sec.vbe
  • %AppDataLocal%\chrome\background.js
  • %AppDataLocal%\{Random Characters}.dat

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It adds the following processes:

  • cmd /c rundll32 "%AppDataLocal%\zb1lUqwR.dat",DllUnInstall %User Temp%\{Malware Name}.exe %AppDataLocal%\zb1lUqwR.dat
  • DllUnInstall %User Temp%\{Malware Name}.exe %AppDataLocal%\zb1lUqwR.dat
  • cmd /c rundll32 "%AppDataLocal%\{Random Character}.dat"

(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

Other Details

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

  • http://dazqc4f140wtl.{BLOCKED}ront.net/RSKl

It does the following:

  • The following command creates the scheduled task:
    • schtasks /create /sc minute /mo 1 /tn "chrome" /tr %AppDataLocal%\chrome\sec.vbe ← Triggered every 1 minute

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 14.514.03
First VSAPI Pattern Release Date: 19 September 2018
VSAPI OPR PATTERN-VERSION: 14.515.00
VSAPI OPR PATTERN DATE: 20 September 2018

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

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 these files

[ 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.
  • %AppDataLocal%\chrome.crx
  • %AppDataLocal%\chrome\content.js
  • %AppDataLocal%\chrome\manifest.json
  • %AppDataLocal%\chrome\page.js
  • %AppDataLocal%\chrome\sec.vbe
  • %AppDataLocal%\chrome\background.js
  • %AppDataLocal%\{Random Characters}.dat

Step 5

Search and delete this folder

[ learnMore ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %AppDataLocal%\chrome

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.INFOSTEAL.TIDAOCN. 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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