BKDR_GRAVITYRAT.B

May 01, 2018
 Analysis by: Patrick Angelo Roderno
 ALIASES:

Trojan-Dropper.Win32.Agent.bjtbmj (KASPERSKY); Trojan.GenericKD.5793454 (BITDEFENDER); Trojan.Gen.2 (NORTON)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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 a website to send and receive information.

  TECHNICAL DETAILS

File Size:

498,176 bytes

Memory Resident:

No

Initial Samples Received Date:

23 Aug 2017

Payload:

Drops files, Connects to URLs/IPs, Collects system information, Executes files

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:

  • %AppDataLocal%\Microsoft\CLR_v7.0_326\18622269_1319089991459758_8391949054533842002_n.jpg - used as a decoy file

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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 creates the following folders:

  • %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump
  • %AppDataLocal%\Microsoft\CLR_v7.0_326
  • %AppDataLocal%\Microsoft\Vshclead

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

Backdoor Routine

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

  • http://{BLOCKED}date.{BLOCKED}pdates.com:46769/Gvty@/newIns3rt.php
  • http://{BLOCKED}tes.{BLOCKED}soft.com:46769/Gvty@/newIns3rt.php
  • http://{BLOCKED}server.{BLOCKED}pdates.eu:46769/Gvty@/newIns3rt.php

Dropping Routine

This Backdoor drops the following files:

  • %AppDataLocal%\Microsoft\CLR_v7.0_326\c08e
  • %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump\Microsoft.Win32.TaskScheduler.dll
  • %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump\Windows Wireless 802.11.exe - Backdoor payload and detected as BKDR_GRAVITYRAT.B

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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 drops the following file, into which it saves gathered information:

  • %AppDataLocal%\Microsoft\Vshclead\Conv - indicates that file scanning is complete
  • %AppDataLocal%\Microsoft\Vshclead\XcatPiles - contains names of all files with specific extensions found in the infected system
  • %AppDataLocal%\Microsoft\Vshclead\SyncFlag - number of uploaded files

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

Download Routine

This Backdoor accesses the following websites to download files:

  • http://{BLOCKED}tes.{BLOCKED}soft.com:46769/Gvty@/payloads/

It saves the files it downloads using the following names:

  • %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump\{Payload Name}

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

Information Theft

This Backdoor gathers the following data:

  • MAC Address
  • Computer Name
  • Username
  • IP Address
  • Current Date
  • Processor ID
  • Processor Name
  • Manufacturer of Processor
  • Maximum Clock Speed of Processor
  • Files with the following extensions in all fixed drives:
    • .docx
    • .doc
    • .ppt
    • .pptx
    • .xlsx
    • .xls
    • .pdf

Other Details

This Backdoor connects to the following URL(s) to get the affected system's IP address:

  • http://{BLOCKED}date.{BLOCKED}pdates.com:46769//Gvty@/ip.php

It adds the following scheduled tasks:

  • Windows Wireless 802.11
    • Executes every logon of affected user
    • Executes the following:
        %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump\Windows Wireless 802.11.exe
  • {Payload Name}
    • Executes every logon of affected user
    • Executes the following:
        %AppDataLocal%\Microsoft\CLR_v7.0_326\CrashDump\{Payload Name}

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.222.06

FIRST VSAPI PATTERN DATE:

30 Apr 2018

VSAPI OPR PATTERN File:

14.223.00

VSAPI OPR PATTERN Date:

01 May 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

Identify and terminate files detected as BKDR_GRAVITYRAT.B

[ 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

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.
  • %System%\Tasks\Windows Wireless 802.11
  • %System%\Tasks\{Payload Name}

Step 5

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.  
  • %AppDataLocal%\Microsoft\CLR_v7.0_326
  • %AppDataLocal%\Microsoft\Vshclead

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_GRAVITYRAT.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 the following Trend Micro Support pages for more information:


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