Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Rimecud.A (Microsoft); Trojan.WIn32.Rimecud.d (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm may be dropped by other malware.

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

  TECHNICAL DETAILS

File Size: 117,760 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 25 Nov 2010

Arrival Details

This worm may be dropped by the following malware:

  • WORM_RIMECUD.L

Installation

This worm injects codes into the following process(es):

  • EXPLORER.EXE

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = "{malware path and file name}.exe"

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

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

The said .INF file contains the following strings:

[autorun]
shell\\Install\\command=kurcina\\prokleta.exe
shell\\open\\command=kurcina\\prokleta.exe
shell\\explore\\command=kurcina\\prokleta.exe
Shell\\open\\command=kurcina\\prokleta.exe
shellexecute=kurcina\\prokleta.exe
open=kurcina\\prokleta.exe
action=Open folder to view files using Windovs Explorer
USEAUTOPLAY=1
Icon=kurcina\\prokleta.exe

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.650.02
FIRST VSAPI PATTERN DATE: 25 Nov 2010

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

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\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Taskman={malware path and file name}.exe

Step 4

Search and delete AUTORUN.INF files created by WORM_RIMECUD.MB that contain these strings

[ Learn More ]
[autorun]
shell\\Install\\command=kurcina\\prokleta.exe
shell\\open\\command=kurcina\\prokleta.exe
shell\\explore\\command=kurcina\\prokleta.exe
Shell\\open\\command=kurcina\\prokleta.exe
shellexecute=kurcina\\prokleta.exe
open=kurcina\\prokleta.exe
action=Open folder to view files using Windovs Explorer
USEAUTOPLAY=1
Icon=kurcina\\prokleta.exe

Step 5

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