WORM_PALEVO.AH

October 22, 2013
 Analysis by: jasperm
 ALIASES:

W32.Pilleuz!gen12 (Symantec); Trojan:Win32/Rimecud.A (Microsoft); P2P-Worm.Win32.Palevo.ayal (Kaspersky)

 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 arrives by connecting affected removable drives to a system. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

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.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

136,192 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

09 Nov 2010

Payload:

Compromises system security

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %Application Data%\rmhzb.exe

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

It is injected into the following processes running in memory:

  • 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 = "%Application Data%\rmhzb.exe"

Propagation

This worm creates the following folders in all removable drives:

  • PRZHI

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

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

  • PRZHI\hladi.exe

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]
;{garbage}
shell\open\command=PRZHI\hladi.exe
;{garbage}
action=Open folderáto view files usingáWindowsáExplorer
;{garbage}
Shell\open\command=PRZHI\hladi.exe
;{garbage}
shellexecute=PRZHI\hladi.exe
;{garbage}
shell\explore\command=PRZHI\hladi.exe
;{garbage}
icon=SHELL32.dll,4
;{garbage}
open=PRZHI\hladi.exe
;{garbage}
USEAUTOPLAY=1

Backdoor Routine

This worm connects to the following websites to send and receive information:

  • {BLOCKED}a.ananikolic.su
  • {BLOCKED}r.pickeklosarske.ru
  • {BLOCKED}e.pornicarke.com
  • {BLOCKED}e.losmibracala.org

  SOLUTION

Minimum Scan Engine:

8.900

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

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 = "%Application Data%\rmhzb.exe"

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.  PRZHI

Step 5

Search and delete AUTORUN.INF files created by WORM_PALEVO.AH that contain these strings

[ Learn More ]
[autorun]
;{garbage}
shell\open\command=PRZHI\hladi.exe
;{garbage}
action=Open folderáto view files usingáWindowsáExplorer
;{garbage}
Shell\open\command=PRZHI\hladi.exe
;{garbage}
shellexecute=PRZHI\hladi.exe
;{garbage}
shell\explore\command=PRZHI\hladi.exe
;{garbage}
icon=SHELL32.dll,4
;{garbage}
open=PRZHI\hladi.exe
;{garbage}
USEAUTOPLAY=1

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_PALEVO.AH. 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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