Establish A Bullet-Proof Security Policy

By Elizabeth M. Ferrarini

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A remote access e-mail gateway will enable your employees to get to their e-mail while they're away from the office. However, this same gateway can also provide intruders with a side door to your network. Likewise, a FTP server will enable customers anywhere to get fixes for your software products instantly. On the other hand, intruders might use your ftp server as an electronic tunnel to valuable corporate data.

With worldwide connections, someone can get into your system in the middle of the night when your building is locked up. The Internet allows the electronic equivalent of an intruder who looks for open windows and doors. Now, a person can check for hundreds of vulnerabilities in just a few hours.

Every organization requires some type of a network site security policy. This will serve to protect its valuable assets -- everything from systems to data. The policy guidelines presented here will help you to establish an enterprise-wide program of how both internal and external users interact with a company's computer network, how the corporate computer architecture topology will be implemented, and where computer assets will be located.

To create a good site policy for computer security, you'll need to do two things: determine the expectations of proper computer and network use, and the procedures to prevent and respond to security incidents. To this end, you, working with your policy committee, need also to consider and to agree upon the following:

Next, you'll need to look at whom, besides yourself, will devise the network site security policy. Policy creation should consist of a representative group of decision makers, technical personnel, and day-to-day users from different levels within the organization. Decision makers should have the power to enforce the policy. Technical personnel should advise on the ramifications of the policy. Likewise, day-to-day users should have a say in how easy or difficult the policy will be to carry out.

Developing a security policy requires that you identify the organizational assets, identify the threats, evaluate the risk, evaluate and implement the tools and technologies available to meet the risks, and develop a usage policy. In addition, you'll need to devise audit procedures for how to do timely reviews of the network and server usage, and how to respond to violations or breakdown. Finally, you'll need to communicate information the policy to everyone (both employees and contractors) who uses the computer network. Plan to review the policy regularly.

Identifying Your Organization's Assets
Your very first step in creating a site security policy consists of compiling a comprehensive list of all the things that need to be protected. Items to consider include:

Evaluating the Risks
Risk analysis involves determining what you'll need to protect, what you'll need to protect it from, and how to protect it. This process forces you to examine all of your risks, ranking each one by severity level.

Possible risks to your network include:

Once you've put the list together, then you'll need a scheme for weighing the risk against the importance of the resource. This exercise will enable the site policy makers to determine how much effort to spend protecting the resource.

Defining a Policy for Acceptable Use
To define a policy for how users will interact with the network, you'll need to consider the following in a policy for acceptable use:

For example, you'll want to cover the following topics when defining the users' rights and responsibilities:

You'll also need to define who'll interpret the policy - an individual or a committee. No matter how well written, the policy will require interpretation from time to time, and this body will serve to review, to interpret, and to revise the policy as needed.

Auditing and Reviewing
To help determine if there is a violation of your security policy, you'll need to depend on the tools included with your computer and network. Most operating systems store numerous bits of information in log files. Examining these log files regularly will often provide the first line of defense for detecting unauthorized use of the system.

By running various monitoring commands at different times throughout the day, you'll make it hard for an intruder to predict your actions. While it may be exceptionally fortuitous that an administrator would catch a violator in their first act, by reviewing log files you'll have a very good chance setting up procedures to identify them at a later date.

Security is a dynamic process. Since it's getting easy to break into network sites through easily available, point-and-click packages, you'll need to do regularly reviews of your network. To this end, you'll need to assemble the core team or a representative subset to review how well things are working, what are the latest threats and security tools, and what are the risks against new assets and business practices.

Enforcing Your Bullet Proof Security

Communicating to Users
The site security policy should include a formal process, which communicates the site security policy to all users. In addition, an educational campaign will make users aware of how computer and network systems are to be used, and how to protect themselves from unauthorized users.

All users will need to know what's considered the proper use of their account or workstation. This communication can most easily be done at the time a user receives their account, by giving them a policy statement. Proper use policies typically should dictate things, such as the following: whether or not the account or workstation may be used for personal activities (such as checkbook balancing or letter writing), whether profit-making activities are allowed, or whether game playing is permitted, etc.

Users should be told how to detect unauthorized access to their account.

If the system prints the last login time when a user logs in, he or she should be told to check that time and note whether or not it agrees with the last time he or she actually logged in.

Ideally, the security policy should strike a balance between protection and productivity.

Responding to Violations
Upon realizing a site security violation, an organization will select a number of responses - both good and sub-optimal. To this end, you should plan responses for different scenarios without the burden of an actual event.

Not only do you need to define actions based on the type of violation, you'll also need to have a clearly defined series of actions for users who violate your computer security policy.

When a policy violation has been detected, you should immediately invoke the pre-defined define course of action. Next, you'll need to have an investigation performed to determine how and why the violation occurred, and what is the appropriate corrective action. The type and severity of action taken will vary depending on the type of violation that occurred.

Discovering Violations: Choose Your Strategy
Once you've determined that the violation it's being perpetrated by someone outside the organization, you'll have to decide what aspect of your security plan should be put in motion. So, you'll need to make sure you site security plan can answer the following questions:

Whenever a site suffers an incident compromising computer security, two opposing pressures may influence the way the organization reacts.

If management fears that the site is sufficiently vulnerable, it may choose a protect-and-proceed strategy. This strategy's primary goal includes protecting and preserving the site facilities and keeping users from experiencing any interruptions, if possible. Active attempts will be made to interfere with the intruder's processes, prevent further access, and begin immediate damage assessment and recovery. This process may involve shutting down the facilities, closing off access to the network, or other drastic measures. Unless the intruder is identified directly, he or she may come back into the site via a different path or may attack another site.

On the other hand, the pursue-and-prosecute strategy adopts the opposite philosophy and goals. The primary goal allows intruders to continue their activities at the site until the site can identify the responsible persons. Law enforcement agencies and prosecutors endorse this approach. However, these agencies can't exempt a site from possible user lawsuits if damage occurs their systems and data.

Prosecution is not the only outcome possible if the intruder is identified. If the culprit is an employee or a student, your organization may choose to take disciplinary actions. To this end, the computer security policy will need to spell out the choices and how they will be selected if an intruder is caught.

Site management will need to carefully consider their approach to this issue before the problem occurs. The strategy adopted might depend upon each circumstance. Or there may be a global policy mandating one approach in all circumstances. You'll need to examine the pos and cons thoroughly. And you'll have to make the users of the facilities aware of the policy so they understand their vulnerabilities no matter which approach is taken.

Strategy Checklists
The following checklists will help a site determine which strategy to adopt: Protect-and-Proceed Strategy or Pursue-and-Prosecute Strategy.

Capturing the Lessons You've Learned
Once you believe that a system has been restored to a safe state, you may not be completely off the hook - there may still be holes and even traps lurking in the system. You'll need to have the system monitored for items that may have been missed during the cleanup stage.

You'll find a security log to be a valuable asset while vulnerabilities are being removed. Keep logs of procedure that have been used to make the system secure again. This information should include command procedures (e.g., shell scripts) that can be run on a periodic basis to recheck the security. Keep logs of important system events. Reference these events to determine the extent of the damage of a given incident.

After an incident, you'll need to write a report describing the incident, method of discovery, correction procedure, monitoring procedure, and a summary of lesson learned. This exercise will provide you with a clear understanding of the problem.

Elizabeth M. Ferrarini is a free-lance writer based in Arlington, Massachusetts.

Editor's note: This article first appeared on Crossnodes.com, an internet.com site.