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WORM_UTORUN.DAM

March 14, 2013
 Analysis by: Michael Cabel
 ALIASES:

W32.SillyDC (Symantec); Worm:Win32/Catchdens.A (Microsoft)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email, Downloaded from the Internet, Dropped by other malware

This worm arrives as attachment to mass-mailed email messages. It 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:

117,760 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Oct 2009

Payload:

Steals information, Connects to URLs/IPs

Arrival Details

This worm arrives as attachment to mass-mailed email messages.

It 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:

  • %Application Data%\{random folder name}\{random filename}.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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows\
load
{random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunServices
{random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrrentVersion\Run
{random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe

NOTES:

It does not continue with its routines if the language of the affected system is not Chinese.

It retrieves the following information:

  • Adaper information
  • Computer name
  • Operating system information

It may also steal sensitive information such as usernames and passwords from the following:

  • Active Directory - Bigfoot, VeriSign, and WhoWhere
  • HTTPMail
  • IMAP
  • Internet Account Manager
  • Internet Explorer
  • NNTP
  • Outlook Express
  • POP3
  • SMTP
  • Windows Live

It may send copies of itself as attachment to email messages.

It connects to the following URL:

  • {root domain}{subdomain}{parameter}

where {root domain} may be any of the following:

  • www.{BLOCKED}a.com
  • {BLOCKED}s.now.cn
  • www.{BLOCKED}8.com
  • {BLOCKED}w.cn
  • www.{BLOCKED}j.cn
  • www.{BLOCKED}per.com
  • www.{BLOCKED}ian.com
  • {BLOCKED}osoft.net
  • www.{BLOCKED}n.net
  • www.{BLOCKED}ill.net

where {subdomain} may be any of the following:

  • /ip/?q=
  • /ip/ipdomain_contents.php?ip_check=
  • /ips.asp?ip=
  • /bianmingfuwu/ip/?s=
  • /Ip.asp?Action=1&IpStr=
  • tools/nslookup.php4?ns_host=
  • scripts/tools/nslookup.asp?Host=
  • nslookup.php?host={parameter}&submit=Nslookup!
  • cgi-bin/checkhost?keyword=
  • nslookup.php?choice=host&hostip=

where {parameter} may be any of the following:

  • www.{BLOCKED}a.com
  • www.{BLOCKED}8.net
  • www.{BLOCKED}8.com
  • www.{BLOCKED}3.cn
  • {BLOCKED}er.cn

It performs GET requests to the formed URL. It then parses the contents to search for the following strings:

  • whois.php?ip=
  • ip_add.asp?ip=
  • IpStr=
  • Address:
  • ospace;
  • address 
  • address:

It uses the domains/IP addresses/names that it finds as values for the content of the email that it sends.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

6.590.01

FIRST VSAPI PATTERN DATE:

30 Oct 2009

VSAPI OPR PATTERN File:

6.591.00

VSAPI OPR PATTERN Date:

31 Oct 2009

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

Identify and terminate files detected as WORM_UTORUN.DAM

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\Microsoft\Windows NT\CurrentVersion\Windows\load
    • {random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices
    • {random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrrentVersion\Run
    • {random filename}.exe = %Application Data%\{random folder name}\{random filename}.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_UTORUN.DAM. 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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