Analysis by: Wilbert Vidal
ALIASES:

Riskware/RemoteAdmin_Ammyy (Fortinet); a variant of Win32/RemoteAdmin.Ammyy.H potentially unsafe (ESET-NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 667,104 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 Jun 2018

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.

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

Other System Modifications

This Backdoor adds the following registry entries:

HKLM\SYSTEM\ControlSet001\
services
netsxuid = 53576297

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • File Manager
  • View Screen
  • Remote Control
  • Audio Chat
  • RDP Sessions
  • Service - Install/Start/Stop/Remove
  • Disable desktop background
  • Disable desktop composition
  • Disable visual effects
  • Show tooltip - mouse cursor blinking cause

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.{BLOCKED}.86.140

Information Theft

This Backdoor gathers the following data:

  • Victim ID
  • OS
  • Privilege
  • Username
  • Computer name
  • Antivirus product name obtained via WMI query
  • 1 if a usable smart-card is inserted into a reader, 0 otherwise
  • Malware build time

Other Details

This Backdoor accepts the following parameters:

  • -service
  • -dosas

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.308.06
FIRST VSAPI PATTERN DATE: 11 Jun 2018
VSAPI OPR PATTERN File: 14.309.00
VSAPI OPR PATTERN Date: 12 Jun 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

Restart in Safe Mode

[ Learn More ]

Step 4

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\SYSTEM\ControlSet001\services
    • netsxuid = 53576297

Step 5

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


Did this description help? Tell us how we did.