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WORM_GOLROTED.YYZM

July 12, 2015
 Analysis by: Jon Dexter Laurin
 ALIASES:

TrojanSpy:MSIL/Golroted.A (Microsoft); Trojan.Win32.Pakes.aoff (Kaspersky); Troj/MSIL-DJS (Sophos); a variant of MSIL/Injector.KHF trojan (ESET-NOD32); Trojan.Win32.Pakes (VIPRE)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

1,212,719 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Jul 2015

Arrival Details

This worm 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 worm drops the following copies of itself into the affected system and executes them:

  • %User Profile%\Templates\takshost.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops the following files:

  • %Application Data%\pid.txt
  • %Application Data%\pidloc.txt
  • %User Temp%\holdermail.txt (deleted afterwards)
  • %User Temp%\holderwb.txt (deleted afterwards)
  • %User Temp%\{random number}.ini (deleted afterwards)

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other System Modifications

This worm adds the following registry keys:

HKLM\SOFTWARE\Microsoft\
ESENT\Process\takshost

HKLM\SOFTWARE\Microsoft\
ESENT\Process\takshost\
DEBUG

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\Sys.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}oneyblongstome.netai.net/gracemoni/PHP/index.php?

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.748.02

FIRST VSAPI PATTERN DATE:

21 Jun 2015

VSAPI OPR PATTERN File:

11.749.00

VSAPI OPR PATTERN Date:

22 Jun 2015

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

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

Restart in Safe Mode

[ Learn More ]

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.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ESENT\Process
    • takshost

Step 5

Search and delete these files

[ 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.
  • %Application Data%\pid.txt
  • %Application Data%\pidloc.txt
  • %User Temp%\holdermail.txt
  • %User Temp%\holderwb.txt
  • %User Temp%\{random number}.ini

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_GOLROTED.YYZM. 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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