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Backdoor.ASP.CHOPSHELL.C

May 14, 2020
 Analysis by: Mc Justine De Guzman
 ALIASES:

Trojan:JS/Chopper!dha (Microsoft) ; PHP/ChinaChopper (NAI)

 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 takes advantage of certain vulnerabilities.

  TECHNICAL DETAILS

File Size:

69 bytes

File Type:

ASP

Memory Resident:

No

Initial Samples Received Date:

12 May 2020

Payload:

Exploits vulnerability

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.

Backdoor Routine

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

  • Execute Arbitrary Shell Commands
  • Manage Files
    • Upload
    • Download
    • Edit
    • Delete
    • Copy
    • Rename
    • File time modification
  • Manage Database
    • View
    • Create
    • Edit
    • Delete
  • View Website

Other Details

This Backdoor does the following:

  • It contains the following commands to execute arbitrary codes:
    • "eval(Request.Item["{string}"],"unsafe")"

It takes advantage of the following vulnerabilities:

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.868.04

FIRST VSAPI PATTERN DATE:

14 May 2020

VSAPI OPR PATTERN File:

15.869.00

VSAPI OPR PATTERN Date:

15 May 2020

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

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

Close all opened browser windows

Step 4

Download and apply these security patches Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors. https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0604

Step 5

Scan your computer with your Trend Micro product to delete files detected as Backdoor.ASP.CHOPSHELL.C. 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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