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PE_MUMAWOW.C

October 12, 2012
 ALIASES:

Virus:Win32/Cekar.L (Microsoft); W32.Mumawow.A!inf (Symantec); Virus.Win32.Downloader.av (Kaspersky); Virus.Win32.Cekar.gen (v) (Sunbelt); Win32.Downloader.Patch.A (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This file infector 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:

1,127,992 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

05 May 2012

Arrival Details

This file infector 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 file infector creates the following folders:

  • %User Temp%\chrome_10881
  • %User Temp%\10881

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Other System Modifications

This file infector deletes the following files:

  • %User Temp%\chrome_installer.log

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Google

HKEY_CURRENT_USER\Software\Google\
Update

HKEY_CURRENT_USER\Software\Google\
Update\ClientState

HKEY_CURRENT_USER\Software\Google\
Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Google\
Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
InstallerResult = "1"

HKEY_CURRENT_USER\Software\Google\
Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
InstallerError = "c"

HKEY_CURRENT_USER\Software\Google\
Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
InstallerResultUIString = "{random characters}"

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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_CURRENT_USER\Software
    • Google
  • In HKEY_CURRENT_USER\Software\Google
    • Update
  • In HKEY_CURRENT_USER\Software\Google\Update
    • ClientState
  • In HKEY_CURRENT_USER\Software\Google\Update\ClientState
    • {8A69D345-D564-463c-AFF1-A69D9E530F96}

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_CURRENT_USER\Software\Google\Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
    • InstallerResult = "1"
  • In HKEY_CURRENT_USER\Software\Google\Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
    • InstallerError = "c"
  • In HKEY_CURRENT_USER\Software\Google\Update\ClientState\{8A69D345-D564-463c-AFF1-A69D9E530F96}
    • InstallerResultUIString = "{random characters}"

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 Temp%\chrome_10881
  • %User Temp%\10881

Step 5

Scan your computer with your Trend Micro product to clean files detected as PE_MUMAWOW.C. 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.

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\chrome_installer.log


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