ALIASES:

Backdoor:MSIL/Noancooe.A (Microsoft); GenericRXAA-CZ!660D0964425F (McAfee); Trojan.Nancrat (Symantec); Trojan.MSIL.Agent.fpar (Kaspersky); Troj/NanoCor-BT (Sophos); Trojan.MSIL.NanoCore.B (fs) (Sunbelt)

 PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size: 486,400 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Jan 2020

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 creates the following folders:

  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333
  • %Program Files%\DSL Subsystem
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs\{username}

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Backdoor deletes the following files:

  • %Program Files%\DSL Subsystem\dslss.exe
  • {malware file path and name}:Zone.Identifier
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\DSL Subsystem\dslss.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run
DSL Subsystem = "%Program Files%\DSL Subsystem\dslss.exe"

Dropping Routine

This Backdoor drops the following files:

  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\run.dat
  • %Program Files%\DSL Subsystem\dslss.exe

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Backdoor connects to the following possibly malicious URL:

  • http://strike44rus.{BLOCKED}s.net

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.850

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

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\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • DSL Subsystem = "%Program Files%\DSL Subsystem\dslss.exe"

Step 3

Search and delete these components

[ Learn More ]
There may be some components 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%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\run.dat
  • %Program Files%\DSL Subsystem\dslss.exe

Step 4

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%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333
  • %Program Files%\DSL Subsystem
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\Logs\{username}

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_NOANCOOE.SMUPS. 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:

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Program Files%\DSL Subsystem\dslss.exe
  • {malware file path and name}:Zone.Identifier
  • %Application Data%\0EFADD19-2A94-41FB-8931-F2BBC5D61333\DSL Subsystem\dslss.exe


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