6.6 Countermeasures

Trojan Countermeasures

Avoid opening email attachments received from unknown senders.
Block all unnecessary ports at the hosts and firewall.
Avoid accepting the programs transferred by instant messaging.
Harden weak, default configuration settings and disable unused functionality including protocols and services.
Monitor the internal network traffic for odd ports or encrypted traffic.
Avoid downloading and executing applications from untrusted sources.
Install patches and security updates for the operating systems and applications.
Scan CDs and DVDs with antivirus software before using.
Restrict permissions within the desktop environment to prevent malicious applications installation.
Avoid typing the commands blindly and implementing pre-fabricated programs or scripts.
Manage local workstation file integrity through checksums, auditing, and port scanning.
Run host-based antivirus, firewall, and intrusion detection software.

Most commercial anti-virus products can automatically scan and detect backdoor programs before they can cause damage.
Educate users not to install applications downloaded from untrusted Internet sites and email attachments.
Use anti-virus tools such as McAfee, Norton, etc. to detect and eliminate backdoors.

Install anti-virus software that detects and removes infections as they appear.
Generate an anti-virus policy for safe computing and distribute it to the staff.
Pay attention to the instructions while downloading files or any programs from the Internet.
Update the anti-virus software regularly.
Avoid opening the attachments received from an unknown sender as viruses spread via e-mail attachments.
Possibility of virus infection may corrupt data, thus regularly maintain data back up.
Schedule regular scans for all drives after the installation of anti-virus software.
Do not accept disks or programs without checking them first using a current version of an anti-virus program.
Ensure the executable code sent to the organization is approved.
Do not boot the machine with infected bootable system disk.
Know about the latest virus threats.
Check the DVDs and CDs for virus infection.
Ensure the pop-up blocker is turned on and use an Internet firewall.
Run disk clean up, registry scanner and defragmentation once a week.
Turn on the firewall if the OS used is Windows XP.
Run anti-spyware or adware once in a week.
Do not open the files with more than one file type extension.
Be cautious with the files being sent through the instant messenger.