Keeping your network secure in the current climate of Internet assault is no small job.
Server-based worms are estimated to have cost private industry almost $3 billion in 2001. Code Red alone infected 359,000 servers in under 14 hours, and within 24 hours of Nimda, 50 percent of the infected hosts went offline.
These attacks have reinforced the need for every organization to develop an information security action plan (ISAP). This first involves evaluating, assessing and auditing the existing security environment to identify major and minor problems. Without knowing and understanding the current security posture, it is impossible to identify the most cost-effective solutions to deploy.
It's important to note that it's best to use a credentialed information security professional to create and oversee an enterprise-wide ISAP. The most widely respected and comprehensive is the Certified Information Systems Security Professional (CISSP) administered by the International Information Systems Security Certification Consortium (ISC)² (www.isc².org).
These veteran and well-trained security professionals realize there is no 'silver bullet' in information security. However, using proper diligence to understand an organization's security needs goes a long way to improving protection.
The following are critical first steps of an ISAP a company should take to create a better defense in an increasingly dangerous cyberworld.
First, create a clearly defined security policy that is strictly enforced. Understand that security goes beyond desktop PCs and ensure that the use of all laptops, copiers, fax machines, modems and even printed information is included in the policy. Supply the policy to everyone in the organization, educate all employees about it and enforce it consistently.
The policy is the roadmap to good security, and every employee should review it annually, be provided with opportunities to ask questions, and fully understand the policy. They should acknowledge their understanding of the policy in writing. The policy must become a standard part of the company culture and be enforced at the highest level. Not consistently enforcing policy can be worse than having no policy at all, because it could be used against the company (in litigation) to show that policy is not taken seriously in all cases.
Second, identify an acceptable level of risk and deploy the appropriate level of security. It is no longer adequate for management to proclaim ignorance about potential vulnerabilities in the environment. Due diligence requires management to exercise sound judgment in protecting the environment consistent with the information being processed (i.e. the more sensitive the information, the more safeguards need to put in place).
After assessments have been performed, there are essentially three measures that can be taken. They are to reduce the risk (perform remediation), transfer the risk (take out insurance) or accept the risk (identify cost justification).
If overall risk reaches an unacceptable level, appropriate remediation steps must be taken to get the exposures reduced in severity. If that cannot be done, documentation must be created to identify justification for accepting the risk, or possibly insurance can purchased to transfer the losses associated with the risk to another organization.
Third, access to internal hosts must be controlled and monitored. Are employees only given access to what they need to perform their specific job? Are logs reviewed for inconsistencies and abnormalities on a daily basis?
Since most security breeches are attributed to 'insiders,' it is important to live by an access philosophy of 'least privilege.' Only give users the access they need to do their job. Not only must the data be protected and accountability of who is accessing it be maintained to ensure privacy, but simply tracking problems and events that occur in an environment are easier if it is possible to determine who has access to specific information. Even though incidents of access from outside a company get all the publicity, the most critical protection remains inside. Insider abuse of email or unmonitored Internet access costs a company in several ways beyond the lost employee time, bandwidth, and potential for viruses or worms.
Supplement the authentication and authorization system with audit trails and intrusion detection systems, and use an incident response plan to follow up on suspicious activities and anomalies. Logs can be very large and contain enormous amounts of extraneous information. It is important to install tools that help sift through the abnormalities or make it possible to identify what a normal log looks like and flag unusual activity. Regular review of system logs can mitigate risk.
Fourth, vendor upgrades and software/hardware patches should be tested adequately before migrating to production. Anti-virus tools should be deployed and automatically updated with new signature files.
Changes are constantly occurring in the environment. New software can introduce new vulnerabilities and it is well-known that some software companies do not create secure applications or operating systems. In some cases even the fixes to repair security vulnerabilities have been known to cause system problems.
Having an environment where fixes and new releases of software can be tested first is critical to the stability of any environment. Just as application programs are tested for quality and performance, likewise system and network changes, even if provided by vendors, should go through similar quality assurance measures. The software or fix may not perform the same in a company's environment as it did in the vendors' test lab. At minimum, perform a system test. Make sure the software upgrade does not break the system in its vanilla state. Then test the software with other software that is used in the environment. The software by itself may work, but in conjunction with other software, it or the others may experience problems. Finally, have a clear documentation plan to migrate the changes to production and a contingency plan should problems occur.
Viruses continue to be a major problem for organizations. It is not adequate to simply install a virus tool and assume your virus problems are alleviated. It is not adequate to assume the user will choose to scan and protect their desktop and their data. The virus tool should scan automatically, not requiring end-user intervention to start or stop. In addition, receipt of updated virus signature files should be automated, and virus scanning or filtering products should be implemented at all email gateways.
Even if you have a very sound change to production process and a strong anti-virus program, document and test the implementation of an incident response plan to understand and know exactly how to proceed should trouble strike.
Fifth, be sure default accounts, passwords and settings have been appropriately handled in operating systems, routers, databases and applications.
Keep in mind that almost all operating systems, including third-party applications, come with sample files, many of which are extremely dangerous. Often the default configuration of an operating system is designed for ease of use, not for security. Almost any operating system and many application system installations require a powerful 'administrative' type or 'god-like' account that is needed to complete installation. This account is shipped with a default password, which often is not changed by the network, system or application administrator. It should be changed immediately at initial installation even on test systems. If the account needs to remain in existence it should be tightly locked down, audited and if possible have its default name changed. In addition, it should not be used on a routine basis for administration. Individual administrative accounts should be assigned to authorized users with proper access requirements granted, training provided and responsibilities understood.
In summary, there are numerous measures that can be taken to ensure a company's infrastructure can protect its information assets. This all creates the requirement for a thorough information security action plan to formulate the steps that need to be taken. A certified, qualified, well-trained chief information security officer can usually lead a corporation along a path to protected information assets and a secure business environment.
Ken M. Shaurette, CISSP, CISA, is a senior information security professional based in Madison, Wisconsin, USA. With more than 20 years IT experience, he provides information security and audit advice for companies building information security programs. Contact Ken at: firstname.lastname@example.org.