Analysis by: Francis Xavier Antazo
ALIASES:

TrojanSpy:Win32/Nivdort!rfn (Microsoft); a variant of Win32/Bayrob.BM (ESET); Trojan.Win32.Bayrob.dadh (Kaspersky);

 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 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: 619,008 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 26 Jan 2016
Payload: Connects to URLs/IPs, Displays message/message boxes

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 copies of itself into the affected system and executes them:

  • %System Root%\{random string1}\{random string2}.exe
  • %System Root%\{random string1}\{random string3}.exe
  • %System Root%\{random string1}\{random string4}.exe <- Deleted afterwards

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It drops the following files:

  • %System Root%\{random string1}\{random string5}
  • %Windows%\{random string1\{random string5}
  • %System Root%\{random string1}\{random string6}
  • %System Root%\{random string1}\{random string7}

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It creates the following folders:

  • %System Root%\{random string1}
  • %Windows%\{random string1}

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It displays the following fake error messages:


Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
Support Collector Management Receiver = "%System%\{random string1}\{random string2}.exe"

It adds and runs the following services:

  • Service Name: Shadow Removal Alerts Computer CNG Host
    Display Name: Shadow Removal Alerts Computer CNG Host
    Start Type: 0x2 (Auto Load)
    Binary Pathname: %System Root%\{random string1}\{random string2}.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

Download Routine

This Trojan accesses the following websites to download files:

  • http://{hostname}.net/index.php

NOTES:

The variable {hostname} is generated through concatenating two strings from the following list:

  • consider
  • decide
  • early
  • fancy
  • finish
  • flower
  • friend
  • future
  • health
  • honor
  • laugh
  • laughter
  • leave
  • material
  • mother
  • mountain
  • neither
  • night
  • perhaps
  • possible
  • probably
  • safety
  • seperate
  • severa
  • several
  • simple
  • smell
  • special
  • subject
  • sweet
  • system
  • trust
  • window
  • winter

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.302.06
FIRST VSAPI PATTERN DATE: 28 Jan 2016
VSAPI OPR PATTERN File: 12.303.00
VSAPI OPR PATTERN Date: 29 Jan 2016

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

[ Learn More ]

Step 4

Disable this malware service

[ Learn More ]
    • Shadow Removal Alerts Computer CNG Host

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • Support Collector Management Receiver = "%System%\{random string1}\{random string2}.exe"

Step 6

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.
  • %System Root%\{random string1}
  • %Windows%\{random string1}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_BAYROB.SM7. 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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