PHP_WEBSHELL.KEMR

July 12, 2017
 Analysis by: John Anthony Banes
 Modified by: Byron Jon Gelera
 ALIASES:

PHP/PhpShell.NBD!tr (Fortinet)

 PLATFORM:

Windows, Linux

 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 may be hosted on a website and run when a user accesses the said website.

It does not have any propagation routine.

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

  TECHNICAL DETAILS

File Size:

263 bytes

File Type:

PHP

Memory Resident:

No

Initial Samples Received Date:

02 Jun 2017

Payload:

Executes commands

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.

It may be hosted on a website and run when a user accesses the said website.

Propagation

This Backdoor does not have any propagation routine.

Backdoor Routine

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

  • Execute arbitrary code

Other Details

This Backdoor does the following:

  • It receive codes from the attacker via POST command on this hosted php file with the variable "nnd".

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.512.03

FIRST VSAPI PATTERN DATE:

04 Jul 2017

VSAPI OPR PATTERN File:

13.513.00

VSAPI OPR PATTERN Date:

05 Jul 2017

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

Scan your computer with your Trend Micro product to delete files detected as PHP_WEBSHELL.KEMR. 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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