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Building Internet Firewalls

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Previous: 11.2 Putting Together a Security Policy Chapter 11
Security Policies
Next: 11.4 What If You Can't Get a Security Policy?

11.3 Getting Strategic and Policy Decisions Made

Strategic decisions need to be understood and made by top-level management or they will never be successfully implemented. If you don't have top-level management support for security, you aren't going to have security; it's that simple. Why wouldn't you have support from top-level managers? Probably because you haven't addressed their concerns in ways they understand. Here are some things to consider in making your case.

11.3.1 Involve Everybody Who's Affected

You may be the person with the best understanding of the technical issues, but you aren't necessarily the person with the best understanding of the institution's needs as a whole. Strategic and policy decisions must be made by people working together. You can't just come up with a policy you like, take it around to a lot of people, and have them rubber stamp it. Even if you manage to get them to do it - which may well be more difficult than getting them to help make intelligent decisions - they won't actually follow it.

One major computer manufacturer had a policy forbidding dial-in modems. Unfortunately, the company's centralized dial-in access didn't satisfy all of their programmers. Some of these programmers figured out that, although they couldn't request modem lines, they could redirect existing fax lines to modems, go home at night, and dial up their work computers. Even more unfortunately, a programmer in one of the groups with this habit was fired and proceeded to break into the site. He systematically tried all the phone numbers in the range the company had assigned to fax machines until he connected to one of the redirected ones and got a login prompt from an unsecured machine inside the corporate firewall. The former employee did significant damage before he was detected and shut out. He was able to gain a lot of time because the people trying to shut him out didn't know the modems existed. When they did figure out that modems were involved, the process of getting rid of them all proved to be tedious and prolonged, because lines were diverted only when people planned to use them.

That whole incident was the result of the fact that management and system administrators had a policy that ignored some genuine needs of the people using the computer facility. The official policy required dial-in access to be so secure it was almost completely unusable, and the unofficial policy required dial-in access to be so usable that it was almost completely insecure. If there had been a policy that allowed moderately insecure dial-in access, the break-in might have been avoided, and it certainly would have been easier to detect and stop. It would also have been avoided if the programmers had agreed that security was more important than dial-in access, but that kind of agreement is much harder to achieve than a compromise.

In fact, in this case there wasn't much actual disagreement between the parties involved. If the managers had been asked, they would have said that letting people work from home was important to them; they didn't understand that the existing dial-in system was not providing acceptable service. If the programmers had been asked, they would have said that preventing people from maliciously deleting their work was important to them; they didn't understand the risks of what they were doing. But nobody thought about security and usability at the same time, and the result was pure disaster.

11.3.2 Accept `Wrong' Decisions

You may find that the security policy you come up with is one you don't particularly like. If this happens because the people who made it don't understand what they've done, then you should fight strongly to get it fixed. If, on the other hand, people understand the risks, but they don't share your priorities, put your objections down in writing and go ahead with the policies. Yes, this will sometimes lead to disasters. Nonetheless, if you ask a group to make a decision, you can't insist that it be your decision. You also can't be sure that your way is the only right way.

Sometimes managers have a genuine willingness to accept risks that seem overwhelming to system administrators. For example, one computer manufacturer chose to put one of their large and powerful machines on an unprotected net, and to give out accounts on the machine to customers and prospective customers upon request. The system administrator thought this was a terrible idea and pointed out that the machine was fundamentally impossible to secure; there were a large number of accounts, changing rapidly, with no pattern, and they belonged to people the company couldn't control. Furthermore, the reason the company was giving out test accounts was that the machine was a fast parallel processor, which also meant that it might as well have been designed as the ultimate password-cracking machine. To the system administrator, it seemed extremely likely that once this machine was broken into (which was probably inevitable), it was going to be used as a tool to break into other machines.

A battle ensued, and eventually, a compromise was reached. The machine was made available, but extra security was employed to protect internal networks from it. (This was a compromise because it interfered with employees' abilities to use the machine, which they needed to do to assist the outsiders who were using it.) Management chose to accept the remaining risk that the machine would be used as a platform to attack other sites, knowing that there was a potential for extremely bad publicity as a result.

What happened? Sure enough, the machine was compromised, and was used to attack at least the internal networks. The attacks on the internal networks were extremely annoying, and cost the company money in system administrators' time, but they didn't produce significant damage, and there was little or no bad publicity. Management considered this expense to be acceptable, however, given the sales generated by letting people test-drive the machine. In this case, conflicting security policies were resolved explicitly - by discussion and compromise - and the result was a policy that seemed less strong than the original, but that provided sufficient protection. By openly and intentionally choosing to accept a risk, the company brought it within acceptable limits.

11.3.3 Present Risks and Benefits in Different Ways for Different People

You need to recognize that different people have different concerns. Mostly, these concerns are predictable from their positions, but some are personal. For example, suppose that:

  • Your chief financial officer is concerned about the cost of security, or the cost of not having enough security.

  • Your chief executive officer is concerned about the negative publicity a security incident involving your site could bring, or about potential loss or theft of intellectual property via the Internet.

  • A department chair is concerned that tenure reviews will be revealed.

  • A mid-level manager is concerned his employees are squandering all their time reading Usenet news or surfing the Web.

  • Another mid-level manager is concerned her employees are importing virus-infected PC software from the Internet.

  • Still another mid-level manager is concerned how best to provide technical support to customers over the Internet.

  • A professor is concerned her data won't be accessible from other institutions while she's on sabbatical.

  • An instructor is concerned that students are stealing answers from each other or tests from instructors.

  • Users are concerned about the availability of Internet services they feel are vital for their jobs.

  • Users are concerned they won't be able to work together if there are too many security issues.

  • Students are concerned they won't be able to play with the computers, which is a part of how they learn.

  • Graduate students and project managers are concerned that security measures are going to slow down projects with strict timelines.

You need to take the time to discover all of these different, legitimate concerns and address them. You may also decide there are things that these various people should be worried about, but aren't, because they don't know any better; you have to educate them about those issues. This means you need to take the time to understand their jobs, what they want to accomplish with the network, and how well they appreciate the security issues.

Talk to each of these people in terms they care about. This requires a lot of listening before you ever start talking. To managers, talk about things like probable costs and potential losses; to executives, talk about risk versus benefit; and to technical staff, talk about capabilities. Before you go in with a proposal, be prepared with an explanation that suits your audience's point of view and technical level. If you have trouble understanding or communicating with a particular group, you may find it helps to build a relationship with someone who understands that group and can translate for you.

You're not trying to deceive anybody. The basic information is the same, no matter who you're talking to. On the other hand, if a particular decision saves money and makes for a more enjoyable working environment, you don't go to the chief financial officer and say "We want to do it this way because it's more fun," and then go the programmers and say "We want to do it this way because it's cheaper."

11.3.4 Avoid Surprises

When it comes to security, nobody likes surprises. That's why you need to make sure that the relevant people understand the relevant issues and are aware of, and agree with (or at least agree to abide by), the decisions made concerning those issues.

In particular, people need to know about the consequences of their decisions, including best, worst, and probable outcomes. Consequences that are obvious to you may not be obvious to other people. For example, people who are not extremely UNIX -knowledgeable may be quite willing to give out root passwords. They don't realize what the implications are, and they may be very upset when they find out.

People who have been surprised often overreact. They may go from completely unconcerned to demanding the impossible. One good break-in, or even a prank, can convert people from not understanding all the fuss about passwords to inquiring about the availability of voiceprint identification and machine gun turrets. (It's preferable to get them to make decisions while they are mildly worried, instead of blindly panicked!)

11.3.5 Condense to Important Decisions, with Implications

When you're asking a top manager to decide issues of policy, present only the decision to be made and the pros, cons, and implications of the various options: not a lot of extraneous decisions. For example, you shouldn't waste your CEO 's time by asking him or her to decide whether you should run Sendmail or SMAIL as your mailer; that's primarily a technical issue, and one that should be resolved by the relevant technical staff and managers. On the other hand, you may need to call upon your CEO to decide strategic issues regarding mail, such as whether or not everyone in the organization is to have email access, or only certain people (and if it's to be limited, to whom).

Don't offer people decisions unless they have both the authority and the information with which to make those decisions. Always make it clear why they're being asked to decide (instead of having the decision made somewhere else). In most cases, you want to avoid open-ended questions. It's better to ask "Should we invest money in a single place to be a defense, or should we try to protect all the machines?" than "What do you think we should do about Internet security?" (The open question gives the replier the option of saying "nothing," which is probably not an answer you're going to be happy with.)

11.3.6 Justify Everything Else in Terms of Those Decisions

All of the technical and implementation decisions you make should follow from the high-level guidance you've obtained from your top managers and executives. If you don't see which way you should go with a technical issue because it depends on nontechnical issues, you may need to request more guidance on that issue. Again, explain clearly the problem; the options; and the pros, cons, and implications of each option.

When you explain policies or procedures, explain them in terms of the original decisions. Show people the reasoning process.

11.3.7 Emphasize that Many Issues Are Management and Personnel Issues, not Technical Issues

Certain problems, which some people try to characterize or solve as technical problems, are really management or personnel problems. For example, some managers worry that their employees will spend all their time at work reading Usenet news or surfing the Web. However, this is not a technical problem, but a personnel problem: the online equivalent of employees spending the day at their desks reading the newspaper or doing crossword puzzles.

Another common example of misdirected concern involves managers worrying that employees will distribute confidential information over the Internet. Again, this usually isn't a technical problem; it's a management problem. The same employee who could email your source code to a competitor could also carry it out the door in his pocket on an 8mm tape (generally far more conveniently and with less chance of being caught). It is irrational to place technological restrictions on information that can be sent out by email unless you also check everybody's bags and pockets as they leave the premises.

11.3.8 Don't Assume That Anything Is Obvious

Certain things that seem obvious to a technical person who is interested in security may not be at all obvious to nontechnical managers and executives. As we've mentioned, it's obvious to anyone who understands IP that packet filtering will allow you to restrict access to services by IP addresses, but not by user (unless you can tie specific users to specific IP addresses). Why? Because "user" is not a concept in IP , and there's nothing in the IP packet that reflects what "user" is responsible for that packet. Conversely, certain things that seem obvious to managers and executives are not at all obvious to technical staff, e.g., that the public's perception (which is often incomplete or simply incorrect) of a problem at your company is often more important than the technical "truth" of the matter.

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