Analysis by: Rheniel Rhay Ramos

 ALIASES:

W97M/HWPS.AGN (Avira); Trojan.HTML.Agent.mb (Kaspersky); TrojanDropper:Win32/Agent (Microsoft); Trojan.Mdropper (Symantec)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This malware is associated with attacks involving malicious attachments for Hangul Word Processor (HWP). In the attack, PostScript is used to gain access to a victim's machine.

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: 379,392 bytes
File Type: Other
Memory Resident: No
Initial Samples Received Date: 06 Jul 2017
Payload: Drops 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 drops the following files:

  • %User Startup%\HncCheck.lnk -> taget location: C:\Windows\System32\rundll32.exe %temp%\..\HncBB80.bin,MainCallBack
  • %AppDataLocal%\HncBB80.bin -> detected as TROJ_HWDOOR.A

It drops and executes the following files:

  • %User Temp%\Hnc\BinData\EMB00000{7 random hex}.ps

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

It injects threads into the following normal process(es):

  • explorer.exe

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • www.kbautosys.com

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 12.940.03
FIRST VSAPI PATTERN DATE: 06 Jul 2017
VSAPI OPR PATTERN File: 12.941.00
VSAPI OPR PATTERN Date: 07 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

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

Search and delete these files

[ Learn More ]
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%\Hnc\BinData\EMB00000{7 random hex}.ps
  • %User Startup%\HncCheck.lnk
  • %AppDataLocal%\HncBB80.bin

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_MALEPS.B. 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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