WORM_OSCARBOT

Trend Micro spotted the first OSCARBOT malware in 2007, spreading via the ASN.1 Bitstring Overflow vulnerability found in Windows NT, 2000, and XP systems. Other OSCARBOT malware propagates using any of the following routes:

• Via IRC

• Via instant messengers

• Via removable drives

Its main objective is to execute commands on an infected computer by way of connecting to a specific IRC server and channel. When connected, the malware receives commands issued on the channel and executes these commands on the computer it infects. The commands executed vary but may include any of the following:

• Downloading/uploading of files

• Performing SYN flood attacks

• Performing DDOS attacks

• Spreading itself via MSN, AIM messengers

• Stealling passwords from Protected Storage

Installation

This worm drops the following file(s)/component(s):

• %User Temp%\rmme{4 numbers}.bat

(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 drops the following copies of itself into the affected system:

• %Application Data%\afd.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.)

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
Cftmon32 = "%Application Data%\afd.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Terminal Server\
Install\Software\Microsoft\
Windows\CurrentVersion\Run
Cftmon32 = "%Application Data%\afd.exe"

Other System Modifications

This worm creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:Cftmon32"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
{malware path}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:1"

Propagation

This worm creates the following folders in all removable drives:

• Folder
• Folder\SubFolder

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

• Folder\SubFolder\file.exe

Backdoor Routine

This worm connects to any of the following IRC server(s):

• one.{BLOCKED}t.com