Backdoor.Win64.BADIIS.A

February 23, 2023
 Analysis by: Arianne Grace Dela Cruz
 ALIASES:

Backdoor:Win32/IISBackdoor.A (MICROSOFT); UDS:Backdoor.Win64.BadIIS.ao (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

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:

20,992 bytes

File Type:

DLL

Memory Resident:

No

Initial Samples Received Date:

13 Aug 2021

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 files:

  • %Temp%\creds.db → log file of HTTP requests

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

Other Details

This Backdoor does the following:

  • It parses all incoming HTTP requests with the string "password" on its body.
  • It checks for a specific password in the following header in order to proceed with its backdoor routine:
    • X-Password
  • It checks the following headers to identify the backdoor command to be executed:
    • X-Chrome-Variations
  • It interprets the following messages as its backdoor command:
    • CMD| - execute arbitrary command via cmd.exe
    • PIN| - dumps specific content into a file with a specified name
    • INJ| - inject codes to a legitimate %System%\credwiz.exe process executed
    • DMP| - dump the contents of the log file

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It requires being hosted on a web server in order to proceed with its intended routine.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.908.05

FIRST VSAPI PATTERN DATE:

16 Aug 2021

VSAPI OPR PATTERN File:

16.909.00

VSAPI OPR PATTERN Date:

17 Aug 2021

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     TROJ.Win32.TRX.XXPE50FFF065

Step 2

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 3

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 4

Search and delete this file

[ 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.
  • %Temp%\creds.db

Step 5

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win64.BADIIS.A. 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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