Hi quiet_bear,

As can be seen from the Sucuri report, your Joomla version is outdated and vulnerable,
Web application details:
Application: Joomla! 1.5 - Open Source Content Management - http://www.joomla.org

Web application version:
Joomla Version 1.5.8 to 1.5.14 for: htxp://www.bsm.bialystok.pl/media/system/js/caption.js
Joomla Version 1.5.9 to 1.5.13 for: htxp://www.bsm.bialystok.pl/language/en-GB/en-GB.ini
Joomla version outdated: Upgrade required.

You could scan with OWASP Joomla!Security Scanner, download http://sourceforge.net/projects/joomscan/files/latest/download (developer d0ubl3_h3lix)

polonus