- Clearance: Security level of the subject.
- Need – to – know: The approved formal access level.
Attackers employ a number of tricks and techniques for gaining unauthorized access to the resources and information of the company. Necessary countermeasures need to be taken so that these threats can be identified and eliminated.
There are different modes of unauthorized access as discussed further:
- Unauthorized disclosure of information: The disclosure of sensitive information might be intentional or accidental. Whatever the cause maybe, the results are always same. The individual get the information that they were not intended to access. A large part of the access control is about preventing such types of incidents from taking place. People might use different kinds of media for sharing information around the organization such as hard drives, floppy disks, shares on servers and so on. These media might contain sensitive information that might get in to the hand of the people for which it is not intended. Also new employees might be assigned old computers to work up on which might also contain some sensitive information stored by the former employees. Object reuse is one example where some object containing sensitive information might be used by other subjects.
- Emanation security: Attackers can even intercept electrical signals for stealing the information. The signals are radiated by the computers and other devices which can be intercepted by attackers by means of some specialized equipment. Using the right software as well as hardware, this information can be reconstructed without coming into the knowledge of the users using it. Main countermeasures include control zones, white noise and the TEMPEST.
- Man – in – the – middle attacks: An intruder drops in to a conversation going on between two hosts and intercepts the messages. Sequence numbers and digital signals can be used as countermeasures.
- Sniffing: This is a type of passive attack when the network is monitored by the intruder for gaining info concerning the victim and is used for attacking later. Data encryption can be done for preventing all this.
- War dialing: This is a kind of brute force attack where a program is used by the attacker using which it dials a large bank of phone numbers. This is done to check which phone belongs to a particular modem. Using this, the attacker can gain access to the network. Not publicizing telephone numbers is one countermeasure.
- Ping of death: In this Denial – of – service attack, the attacker sends oversized ICMP packets to the victim host. If the host is not familiar with how to handle such large packets, it may reboot or freeze. Implementing ingress filtering and patching the systems are some counter measures for detecting such oversized ICMP packets. Another type of DoS attack is the WinNuk.