Trojan-PSW.Win32.Delf.fz is a delphi application that drops and
loads a password stealing component on infected system.
Trojan-PSW.Win32.Delf.fz is a PE executable written in delphi.
The trojan file is unpacked and about 51 kilobytes long.
Installation to System
When the trojan file is executed, it makes a copies itself as
'explorer.exe' to Windows system folder. It then adds the
following registry key to ensure it will be started next time
Windows is started:
[HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell]
"Explorer.exe" = "C:\Windows\system32\Explorer.exe"
The trojan also adds an entry to the win.ini file using the Windows
API call WritePrivateProfileStringA from the Kernel32.dll. The entry
will look like this:
[windows]
Load="C:\Windows\system32\Explorer.exe"
As win.ini is not supported by Windows NT, 2000 and XP, on these
operating system the changes will be added to the Registry.
The trojan also drops a file 'htdll.dll' from its resource to
Windows system folder. This DLL is is the password stealing
component.
Payload
Trojan-PSW.Win32.Delf.fz activates the dropped DLL which starts
to monitor Internet Explorer for account information (usernames,
passwords). The DLL is activated using a fixed URL that is used
to later send collected information to trojan author. The DLL can
also send collected information using e-mails.
The trojan tries to kill several firewalls and other security
related software in the installation phase to make sure the DLL
can connect to remote server.
The trojan also tries to download and activate additional component
during the installation. At the time of this writing, this component
is not available.
F-Secure Anti-Virus detects this trojan with the following
update:
[FSAV_Database_Version]
Version=2005-05-04_02
Technical details:
Jarkko Turkulainen, May 18th, 2005;
F-Secure Corporation
