Firewalls are computer devices that control computer traffic allowed into and out of a company’s network, as well as traffic into more sensitive areas within a company’s internal network. A firewall examines all network traffic and blocks those transmissions that do not meet the specified security criteria. All systems must be protected from unauthorized access from the Internet, whether entering the system as e-commerce, employees’ Internet-based access through desktop browsers, or employees’ e-mail access. Often, seemingly insignificant paths to and from the Internet can provide unprotected pathways into key systems. Firewalls are a key protection mechanism for any computer network.

Hackers (external and internal to a company) often use vendor default passwords and other vendor default settings to compromise systems. These passwords and settings are well known in hacker communities and easily determined via public information.

Encryption is a critical component of cardholder data protection. If an intruder circumvents other network security controls and gains access to encrypted data, without the proper cryptographic keys, the data is unreadable and unusable to that person. Other effective methods of protecting stored data should be considered as potential risk mitigation opportunities. For example, methods for minimizing risk include not storing cardholder data unless absolutely necessary, truncating cardholder data if full PAN is not needed, and not sending PAN in unencrypted e-mails.

Sensitive information must be encrypted during transmission over networks that are easy and common for a hacker to intercept, modify, and divert data while in transit.

Many vulnerabilities and malicious viruses enter the network via employees’ e-mail activities. Anti-virus software must be used on all systems commonly affected by viruses to protect systems from malicious software.

Unscrupulous individuals use security vulnerabilities to gain privileged access to systems. Many of these vulnerabilities are fixed by vendor-provided security patches. All systems must have the most recently released, appropriate software patches to protect against exploitation by employees, external hackers, and viruses. Note: Appropriate software patches are those patches that have been evaluated and tested sufficiently to determine that the patches do not conflict with existing security configurations. For in-house developed applications, numerous vulnerabilities can be avoided by using standard system development processes and secure coding techniques.

This requirement ensures critical data can only be accessed by authorized personnel.

Assigning a unique identification (ID) to each person with access ensures that actions taken on critical data and systems are performed by, and can be traced to, known and authorized users.

Any physical access to data or systems that house cardholder data provides the opportunity for individuals to access devices or data and to remove systems or hardcopies, and should be appropriately restricted.

Logging mechanisms and the ability to track user activities are critical. The presence of logs in all environments allows thorough tracking and analysis when something does go wrong. Determining the cause of a compromise is very difficult without system activity logs.

Vulnerabilities are being discovered continually by hackers and researchers, and being introduced by new software. Systems, processes, and custom software should be tested frequently to ensure security is maintained over time and with any changes in software.

A strong security policy sets the security tone for the whole company and informs employees what is expected of them. All employees should be aware of the sensitivity of data and their responsibilities for protecting it.

As referenced in Requirement 12.8, all service providers with access to cardholder data (including hosting providers) must adhere to the PCI DSS. In addition, Requirement 2.4 states that hosting providers must protect each entity’s hosted environment and data. Therefore, hosting providers must give special consideration to the following::