BKDR_NOANCOOE.THAOCAI

 Analysis by: Michael Jhon Ofiaza

 ALIASES:

HEUR:Trojan.Win32.Generic (Kaspersky)

 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:

Dropped by other malware, Downloaded from the Internet


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

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

826,003 bytes

File Type:

Other

Memory Resident:

Yes

Initial Samples Received Date:

02 Jan 2019

Payload:

Connects to URLs/IPs, Compromises system security, Steals information, Drops 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 the following copies of itself into the affected system:

  • %Program Files%\{String1}\{String2}.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

It adds the following processes:

  • tross.sfx.exe -p126 -d%temp%

It creates the following folders:

  • %Application Data%\{GUID}
  • %Application Data%\{GUID}\Logs
  • %Application Data%\{GUID}\Logs\{user name}
  • %Program Files%\{String1}{String2}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

Autostart Technique

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

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{String1}{String3} = %Program Files%\{String1}{String3}\{String1}{String2}.exe

Backdoor Routine

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

  • Manage its backdoor file:
    • Update itself
    • Restart connection
    • Disconnect
    • Terminate itself
    • Uninstall itself
  • System Control:
    • Restart machine
    • Shutdown machine
    • Lock machine
    • Browse files and folders
    • Task Manager
    • Edit registry
    • Remote console (Command Prompt)
    • Remote execute a file
    • Remote execute a script (Batch, HTML, VBS, Python, Java, PHP)
    • Remote control the machine
    • Remote control mouse
    • Recover browser passwords
    • Log Keystrokes
    • View the screen/webcam
    • Listen to audio/microphone
    • Send Messages / Chat with the malicious user
    • Swap/Unswap mouse buttons
    • Open/Close CD/DVD Tray

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

  • {BLOCKED}ra.hopto.org:4722
  • {BLOCKED}n.ddns.net:4722

Dropping Routine

This Backdoor drops the following files:

  • %Application Data%\{GUID}\catalog.dat
  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\settings.bin
  • %Application Data%\{GUID}\Logs\{user name}\KB_{Random numbers}.dat

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Information Theft

This Backdoor gathers the following information on the affected computer:

  • Computer Name
  • User Name
  • CPU Usage
  • Available and Free Memory
  • Active Window Title
  • Operating System Version
  • System Type (32-bit or 64-bit)
  • Malware Filename
  • Installed Anti-Virus/Anti-Spyware

Other Details

This Backdoor does the following:

  • String1:
    • dhcp
    • upnp
    • tcp
    • udp
    • saas
    • iss
    • smtp
    • dos
    • dpi
    • pci
    • scsi
    • wan
    • lan
    • nat
    • imap
    • nas
    • ntfs
    • wpa
    • dsl
    • agp
    • arp
    • ddp
    • dns
  • String2:
    • ss
    • mon
    • Mgr
    • sv
    • svc
    • host
  • String3:
    • Subsystem
    • Monitor
    • Manager
    • Service
    • Host
  • The SFX file contains the following:
    • fdd.bat -> contains the password of tross.sfx.exe, executed to extract tross.sfx.exe
    • tross.sfx.exe

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.728.02

FIRST VSAPI PATTERN DATE:

03 Jan 2019

VSAPI OPR PATTERN File:

14.729.00

VSAPI OPR PATTERN Date:

04 Jan 2019

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 delete files detected as BKDR_NOANCOOE.THAOCAI using either the Startup Disk or Recovery Console

[ 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\Software\Microsoft\Windows\CurrentVersion\Run
    • {String1}{String3} = %Program Files%\{String1}{String3}\{String1}{String2}.exe

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.
  • %Application Data%\{GUID}
  • %Program Files%\{String1}{String2}

Step 6

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