ALIASES:

HEUR:Downloader.Win32.Agent.vho (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Potentially Unwanted Application 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: 1,133,400 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 May 2020

Arrival Details

This Potentially Unwanted Application 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 Potentially Unwanted Application creates the following folders:

  • %User Profile%\UIDowner
  • %System Root%\Download
  • %User Temp%\Zk9rxT53nxfn2i1Y

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Potentially Unwanted Application adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\RFC1156Agent\CurrentVersion\
Parameters
TrapPollTimeMilliSecs = "15000"

HKEY_CURRENT_USER\Software\UIDowner
usestime = "1"

Dropping Routine

This Potentially Unwanted Application drops the following files:

  • %AppDataLocal%\GDIPFONTCACHEV1.DAT

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Potentially Unwanted Application connects to the following possibly malicious URL:

  • http://downloader.{BLOCKED}api.com/client/error?{random characters}
  • http://downloader.{BLOCKED}api.com/client/ad/28?{random characters}
  • http://static.{BLOCKED}api.com/upload/xml/360.xml?{random characters}
  • http://source.{BLOCKED}api.com/theme/2200417.dat
  • http://img.{BLOCKED}api.com/{random path}
  • http://downloader.{BLOCKED}api.com/client/next?{random characters}

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\RFC1156Agent\CurrentVersion\Parameters
    • TrapPollTimeMilliSecs = "15000"
  • In HKEY_CURRENT_USER\Software\UIDowner
    • usestime = "1"

Step 3

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.
  • %AppDataLocal%\GDIPFONTCACHEV1.DAT

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.
  • %User Profile%\UIDowner
  • %System Root%\Download
  • %User Temp%\Zk9rxT53nxfn2i1Y

Step 5

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.DOWNER.AO. 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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