PDF_DOCDROP.YYSZT

 Analysis by: Cris Nowell Pantanilla
 Modified by: Johnlery Triunfante

 ALIASES:

Trojan-Downloader.PDF.Agent.et (KASPERSKY); TrojanDownloader:O97M/Donoff!rfn (MICROSOFT); Trojan.Pidief (NORTON)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via email

This Trojan arrives as an attachment to email messages mass-mailed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size:

64,566 bytes

File Type:

PDF

Memory Resident:

No

Initial Samples Received Date:

11 May 2017

Payload:

Drops files

Arrival Details

This Trojan arrives as an attachment to email messages mass-mailed by other malware/grayware or malicious users.

Installation

This Trojan drops and executes the following files:

  • %User Temp%\A9R{Random}.tmp\V6KCOJ.docm ← contains malicious macro, detected as W2KM_DLOADR.JLT

It creates the following folders:

  • %User Temp%\A9R{Random}.tmp

(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.)

Other Details

This Trojan does the following:

  • It deletes the created folder and dropped file once it is closed.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.400.05

FIRST VSAPI PATTERN DATE:

12 May 2017

VSAPI OPR PATTERN File:

13.401.00

VSAPI OPR PATTERN Date:

13 May 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

Remove malware/grayware files dropped/downloaded by PDF_DOCDROP.YYSZT. (Note: Please skip this step if the threats listed below have already been removed.)

    • W2KM_DLOADR.JLT

Step 4

Search and delete these folders

[ Learn More ]
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.
  • %User Temp%\A9R{Random}.tmp

Step 5

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%\A9R{Random}.tmp\465895.docm

Step 6

Scan your computer with your Trend Micro product to delete files detected as PDF_DOCDROP.YYSZT. 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 7

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


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