SEMANTIC SECURITY

SEMANTIC SECURITY

-and risks grow larger every year. Not only do we have cheaper, faster computers (remember Moore’s Law), we also have more data,

more systems for reporting and querying that data, and easier, faster, and broader communication. We have organizational

data in the cloud that is not physically under our control. A11 of

these combine to increase the chances that private or propri- etary information is inappropriately divulged.

Access security is hard enough: How do we know that

the person (or program) who signs on as Megan Cho really is Megan Cho? We use passwords,

but files of passwords can be sto- len, Setting that issue aside, we need to know that Megan Cho’s permissions are set appropriately. Suppose Megan works in the HR department, so she has access to personal and private data of other employees. We need to design the reporting system so that Megan can access all of the data she needs to do her job, and no more.

Also, the delivery system must be secure. A BI server is an obvious and juicy target for any would-be intruder, Someone can break in and change access permissions. Or a hacker could pose as someone else to obtain reports. Application servers help the authorized user, resulting in faster access to more informa- tion. But without proper security reporting, servers also ease the intrusion task for unauthorized users.

AII of these issues relate to access security. Another dimen- sion to security is equally seri- ous and far more problematic:

semantic security. Semantic security concerns the unr- tended release of protected information through the relea>: of a combination of reports or documents that are indeper’ dently not protected. The term data triangulation is al’: used for this same phenomenon.

Take an example from class. Suppose I assign a grou- project, and I post a list of groups and the names of studen–. assigned to each group. Later, after the assignments ha’,. been completed and graded, I post a list of grades on tt. Web site. Because of university privacy policy, I cannot pc,.;”

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: grades by student name or identifier, so instead I post -: grades for each group. Ifyou want to get the grades for -.ch student, all you have to do is combine the list from .:Ctur€ 5 with the list from Lecture 10. You might say that -: release of grades in this example does no real harm- ..er all, it is a list of grades from one assignment.

But go back to Megan Cho in HR. Suppose Megan , aluat€S the employee compensation program. The COO ‘.iieves salary offers have been inconsistent over time . .d that they vary too widely by department. Accordingly, ‘e COO authorizes Megan to receive a report that lists .;laryOfferAmount and OfferDate and a second report that

;ts Department and AuerageSalary.

Those reports are relevant to her task and seem in- ‘ rcuous enough. But Megan realizes that she could use the -tbrmation they contain to determine individual salaries-

-lbrmation she does not have and is not authorized to ‘.ceive. She proceeds as follows.

Like all employees, Megan has access to the employee

-,rectory on the Web portal. Using the directory, she can ctain a list of employees in each department, and using

re facilities of her ever-so-helpful report-authoring system .re combines that list with the department and average- ,rlary report. Now she has a list of the names of employees r a group and the average salary for that group.

Megan’s employer likes to welcome new employees to

:re company. Accordingly, each week the company pub-

-shes an article about new employees who have been hired.

– he article makes pleasant comments about each person .nd encourages employees to meet and greet them.

In your own words, explain the difference befi,veen ac- cess security and semantic security.

VVtry do reporting systems increase the risk of semantic security problems?

\.&rhat can an organization do to protect itself against ac-

cidental losses due to semantic security problems?

D!SiCTJSSIctN OUEEiTIONS

Megan, however, has other ideas. Because the report is published on SharePoint, she can obtain an electronic copy of it. It’s an Acrobat report, and using Acrobat’s handy

Search feature, she soon has a list of employees and the weektheywere hired.

She now examines the report she received for her study, the one that has SalaryOfferAmount and the offer date, and she does some interpretation. During the week

of fuly 21, three offers were extended: one for $35,000, one

for $53,000, and one for $110,000. She also notices from the “New Employees” report that a director of marketing programs, a product test enginee! and a receptionist were

hired that same week. It’s unlikely that they paid the recep-

tionist $110,000; that sounds more like the director of mar-

keting programs. So, she now “knows” (infers) that person’s

salary.

Next, going back to the department report and using the employee directory, she sees that the marketing direc- tor is in the marketing programs department. There are just

three people in that department, and their average salary is

$105,000. Doing the arithmetic, she now knows that the av- erage salary for the other two people is $102,500. If she can find the hire week for one of those other two people, she can

find out both the second and third person’s salaries. You get the idea. Megan was given just two reports to

do her job. Yet she combined the information in those re- ports with publicly available information and was able to deduce salaries, for at least some employees. These salaries

are much more than she is supposed to know. This is a se- mantic security problem.

\A/hat legal responsibility does an organization have to protect against semantic security problems?

Suppose semantic security problems are inevitable. Do

you see an opportunity for new products from insurance companies? If so, describe such an insurance product. If not, explainwhy.

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