- In bulk in some form of repository, such as a database or collections of individual files (called data at rest)
- In small quantities being transmitted over a network (called data on the wire)
The ability to gather and share volumes of information was the primary reason behind the creation of the Internet, but such wide availability greatly magnifies the risk of that information being compromised. Attacks against large databases of critical information are on the rise, such as in the following recent cases:
- February, 2003: A hacker broke into the security system of a company that processes credit card transactions, giving the hacker access to the records of millions of Visa and MasterCard accounts.
- June, 2004: More than 145,000 blood donors were warned that they could be at risk for identity theft from a stolen university laptop containing their personal information.
- October, 2004: A hacker accessed names and social security numbers of about 1.4 million Californians after breaking into a University of California, Berkeley computer.
NOTE - Identity theft occurs when someone uses your personal informationósuch as your name, social security number, credit card number, or other identifying informationówithout your permission, frequently to commit fraud or other crimes.
Vulnerabilities of Data on the Wire
Data on the wire is vulnerable to some very focused attacks. Data can be intercepted (sniffed). ARP attacks can be used to sniff information in a switched environment. ARP attacks can also be used to initiate "man in the middle" attacks that can allow an attacker to intercept and potentially modify information in transit.
Sniffing refers to a technique for capturing network traffic. While sniffing can be accomplished on both routed and switched networks, it's much easier in a routed environment:
- Layer 3 devices, such as routers, send information by broadcasting it to every destination on the network, and the destination handles the problem of parsing out the specific information that's needed from the general broadcast.
- In a switched environment, switches send traffic only to its intended host (determined by the destination information in each individual packet).
Operating in a switched environment doesn't totally alleviate the risk of sniffing, but it does mitigate that risk to a large degree.
Most networks today also utilize virtual LAN (VLAN) configurations to segment network traffic and further reduce the risk of sniffing. A VLAN is a switched network that's logically segmented. VLANs are created to provide the segmentation services traditionally provided by routers in LAN configurations. VLANs address scalability, security, and network management. Routers in VLAN topologies provide broadcast filtering, security, address summarization, and traffic-flow management.