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WORM_DDOSER.B

October 09, 2013
 Analysis by: Rika Joi Gregorio
 ALIASES:

Backdoor:Win32/Darkddoser.D(Microsoft), W32/Buzus.BRFP!tr(Fortinet), Trojan-Spy.Win32.Zbot(Ikarus)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Propagates via removable drives


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 executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

288,256 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

07 Nov 2012

Payload:

Connects to URLs/IPs, Steals information

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:

  • %Application Data%\Microsoft\svchost.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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • HelloDDoser

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
svchost.exe = "%Application Data%\Microsoft\svchost.exe"

Propagation

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

  • {Drive Letter}:\svchost.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]
shell=verb
open=svchost.exe
action=Open folder to view files
shell\open=Open
icon=%SystemRoot%\system32\SHELL32.dll,4

Backdoor Routine

This worm opens the following port(s) where it listens for remote commands:

  • TCP port 3085

It executes the following commands from a remote malicious user:

  • Terminate self
  • Sleep
  • Update itself
  • Download Files
  • Download arbitrary files
  • Upload arbitrary files
  • Start SYN flood
  • Start UDP flood

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}logdns.{BLOCKED}me.net

Information Theft

This worm attempts to get stored information such as user names, passwords, and hostnames from the following browsers:

  • Mozilla Firefox

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.328.04

FIRST VSAPI PATTERN DATE:

08 Oct 2013

VSAPI OPR PATTERN File:

10.329.00

VSAPI OPR PATTERN Date:

09 Oct 2013

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • svchost.exe = "%Application Data%\Microsoft\svchost.exe"

Step 4

Search and delete AUTORUN.INF files created by WORM_DDOSER.B that contain these strings

[ Learn More ]


[autorun]
shell=verb
open=svchost.exe
action=Open folder to view files
shell\open=Open
icon=%SystemRoot%\system32\SHELL32.dll,4

Step 5

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