iCal 2.1 Patch 2 installs many files with world-writeable permissions, which allows local users to modify the iCal configuration and execute arbitrary commands by replacing the iplncal.sh program with a Trojan horse.

csstart program in iCal 2.1 Patch 2 searches for the cshttpd program in the current working directory, which allows local users to gain root privileges by creating a Trojan Horse cshttpd program in a directory and calling csstart from that directory.

The GUI installation for iCal 2.1 Patch 2 disables access control for the X server using an "xhost +" command, which allows remote attackers to monitor X Windows events and gain privileges.

csstart program in iCal 2.1 Patch 2 uses relative pathnames to install the libsocket and libnsl libraries, which could allow the icsuser account to gain root privileges by creating a Trojan Horse library in the current or parent directory.