WORM_CARRIER.AS
Microsoft: VirTool:Win32/VBInject.gen!BG; Kaspersky: Worm.Win32.Bybz.ab; Mcafee: W32/Hamweq.worm.aq
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
Propagates via flashdrives
This worm may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system. It uses icons similar to those of legitimate applications to entice a user to click them.
It executes commands from a remote malicious user, effectively compromising the affected system.
TECHNICAL DETAILS
393,256 bytes
PE
Yes
04 Mar 2011
Compromises system security, Launches DoS/DDoS attacks, Terminates processes
Arrival Details
This worm may be downloaded by other malware/grayware/spyware from remote sites.
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%\Microsoft\winlogon.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- GTaAxQEmC:a`/Vz
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
winlogon.exe = "%Application Data%\Microsoft\winlogon.exe"
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- winlogon.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=winlogon.exe
action=Open folder to view files
shell\open=Open
icon=%SystemRoot%\system32\SHELL32.dll,4
It uses icons similar to those of legitimate applications to entice a user to click them.
Backdoor Routine
This worm opens the following port(s) where it listens for remote commands:
- TCP port 3174
It executes the following commands from a remote malicious user:
- Downloads and executes files
- Updates itself
- Launches DDoS attacks (SYN Flood or UDP Flood)
- Stops and uninstalls itself
- Terminates processes
- Sends application privileges and system uptime
- Displays a message box
- Steals Mozilla Firefox password details
- Sends system related information
- Reports which USB infected drives were infected
- Steals Mozilla Firefox saved user names and passwords
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- {BLOCKED}9.{BLOCKED}5.19.117
SOLUTION
8.900
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
Terminate a malware/grayware process
*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.
- %Application Data%\Microsoft\winlogon.exe
Step 3
Delete this registry value
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
- winlogon.exe = %Application Data%\Microsoft\winlogon.exe
- winlogon.exe = %Application Data%\Microsoft\winlogon.exe
Step 4
Search and delete AUTORUN.INF files created by WORM_CARRIER.AS that contain these strings
Step 5
Scan your computer with your Trend Micro product to delete files detected as WORM_CARRIER.AS. 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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