Analysis by: Michael Jhon Ofiaza

ALIASES:

HEUR:Trojan.MSIL.Generic (Kaspersky) , Trojan.Gen.2 (Norton) , Backdoor:MSIL/Noancooe.C (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

  TECHNICAL DETAILS

File Size: 703,488 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Jan 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.

Installation

This Backdoor drops the following copies of itself into the affected system:

  • %Program Files%\{random 3 letters} Service\{random filename}.exe

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It drops the following files:

  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\task.dat
  • %Application Data%\{GUID}\catalog.dat
  • %Application Data%\{GUID}\storage.dat
  • %Application Data%\{GUID}\settings.bin
  • %Application Data%\{GUID}\Logs\{username}\KB_{random 7 numbers}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

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
{random 3 letters} Service = %Program Files%\{random 3 letters} Service\{random filename}.exe

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.100.44

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.926.04
FIRST VSAPI PATTERN DATE: 25 Jan 2018
VSAPI OPR PATTERN File: 13.927.00
VSAPI OPR PATTERN Date: 26 Jan 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_NANOCORE.AUSYVP

[ 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

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
    • {random 3 letters} Service = %Program Files%\{random 3 letters} Service\{random filename}.exe

Step 5

Delete the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. To do this, click Start>Programs>Accessories>System Tools>Scheduled Tasks.
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the .JOB file. To do this, check the value in the Run field.
  4. If found, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel of the Task Scheduler Window, click Task Scheduler Library.
  3. In the upper-middle panel, click a Task.
  4. In the lower middle panel, click the Actions tab
  5. Check if the malware path and file name exists in the task. To do this, check the value in the Details column under the Actions tab.
  6. If found, select the task and press DELETE and click Yes to delete the task.
  7. Repeat the steps above for the remaining tasks.

Step 6

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.
  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\task.dat
  • %Application Data%\{GUID}\catalog.dat
  • %Application Data%\{GUID}\storage.dat
  • %Application Data%\{GUID}\settings.bin
  • %Application Data%\{GUID}\Logs\{username}\KB_{random 7 numbers}

Step 7

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