Analysis by: Adrian Cofreros
ALIASES:

JS/Kryptik.ACD trojan (Eset), Trojan-Dropper.JS.Adultush.k (Kasperksy), Trojan-Downloader.HTA.Agent.ce (v) (Sunbelt)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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

It redirects browsers to certain sites.

  TECHNICAL DETAILS

File Size: Varies
File Type: HTML, HTM
Memory Resident: No
Initial Samples Received Date: 16 Apr 2014
Payload: Connects to URLs/IPs

Arrival Details

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

Installation

This Trojan adds the following folders:

  • {All User's Profile}\Application Data\padpd
  • %System Root%\Program Data\padpd

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It drops the following copies of itself into the affected system:

  • {All User's Profile}\Application Data\padpd\{userid}.h
  • %System Root%\Program Data\padpd\{userid}.h

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following possibly malicious files or file components:

  • {All User's Profile}\Application Data\padpd\{userid}.bat
  • %System Root%\Program Data\padpd\{userid}.bat
  • {All User's Profile}\Application Data\padpd\resta.bat
  • %System Root%\Program Data\padpd\resta.bat
  • {All User's Profile}\Application Data\padpd\2.dat
  • %System Root%\Program Data\padpd\2.dat
  • {All User's Profile}\Application Data\padpd\d.bat
  • %System Root%\Program Data\padpd\d.bat

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
webpadpd = "%System Root%\Program Data\padpd\{userid}"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
webpadpd = "{All User's Profile}\Application Data\padpd\{userid}"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Webpadpd
userid = "{userid}"

HKEY_CURRENT_USER\Software\Webpadpd
tmpdate = "{String value}"

It adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Webpadpd

Other Details

This Trojan redirects browsers to the following sites:

  • http://{BLOCKED}a.us/user/h_check.php?{parameters}
  • http://{BLOCKED}a.us/user/h_info_ajax.php?{parameters}

NOTES:

This malware saves a file in the following folders:

  • {All User's Profile}\Application Data\padpd\bg.jpg
  • %System Root%\Program Data\padpd\bg.jpg

It loads contents from the URL http://www.{BLOCKED}5.com/user/content_ajax_release5.php. The URL where this malware connects to displays pornographic content to lure users to subscribe to their site.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.730.01
FIRST VSAPI PATTERN DATE: 16 Apr 2014
VSAPI OPR PATTERN File: 10.731.00
VSAPI OPR PATTERN Date: 17 Apr 2014

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 and note files detected as HTML_HTAPORN.JA

Step 3

Close all opened browser windows

Step 4

Delete this registry key

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software
    • Webpadpd

Step 5

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • webpadpd = "%System Root%\Program Data\padpd\{userid}"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • webpadpd = "{All User's Profile}\Application Data\padpd\{userid}"

Step 6

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.
  • {All User's Profile}\Application Data\padpd
  • %System Root%\Program Data\padpd

Step 7

Scan your computer with your Trend Micro product to delete files detected as HTML_HTAPORN.JA. 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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