Analysis by: Michael Jay Villanueva

 ALIASES:

Trojan.Malscript (Symantec)

 THREAT SUBTYPE:

Fileless

 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: Dropped by other malware, Downloaded from the Internet

This malware is involved in the filelessly-installed backdoor malware attack discovered early August 2017. It is able to install a backdoor malware onto the systems it infects. Users affected by this malware may find their systems exhibiting malicious routines.

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 may be downloaded by other malware/grayware from remote sites.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size: 28,735 bytes
File Type: PS1
Memory Resident: Yes
Initial Samples Received Date: 29 Jun 2017
Payload: Connects to URLs/IPs, 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.

It may be downloaded by the following malware/grayware from remote sites:

It may be downloaded from the following remote sites:

  • https://{BLOCKED}ndo.ru/p1

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Download Routine

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

  • https://{BLOCKED}ndo.ru/favicon

Other Details

This Trojan does the following:

  • The downloaded file (normal file, favicon) will not be saved in the machine, thus, it will be decrypted using RC4 Algorithm, in order to produce a malicious DLL file, which will be injected in the malware's process directly, using ReflectivePEInjection function
  • The decrypted downloaded file is a DLL file, detected as BKDR_ANDROM.ETIN

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.502.07
FIRST VSAPI PATTERN DATE: 29 Jun 2017
VSAPI OPR PATTERN File: 13.503.00
VSAPI OPR PATTERN Date: 30 Jun 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

Identify and terminate files detected as TROJ_PSINJECT.A

[ 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 4

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


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