Question

Suppose we have the following objects with the given integrity levels

Subjects	Integrity Levels
S1	High
S2	Low
S3	Very Low
Objects	Integrity Levels
O1	High
O2	Low
O3	Very Low

At the end of the following sequence of operations, what will be the new integrity levels

assuming the LOMAC policy for subject is in effect?

Operations:

1. S1 writes O1
2. S1 reads O3
3. S2 reads O2
4. S3 writes O2
5. S2 writes O3

Answer 1

As per Low-Water Mark Integrity Audit Policy

The integrity levels of subjects and objects both change to reflect the contamination.

After s observes o, the integrity level of s is lowered to min(i(s), i(o))

After s modifies o, the integrity level of o is lowered to min(i(s), i(o))

Operations:

1. S1 writes O1 = Integrity level of O1 is lowered to min(i(S1), i(O1)) which is High

2. S1 reads O3 = Integrity level of S1 is lowered to min(i(S1), i(O3)) which is Very Low

3. S2 reads O2= Integrity level of S2 is lowered to min(i(S2), i(O2)) which is Low

4. S3 writes O2 = Integrity level of O2 is min(i(S3), i(O2)) which is i(S3) i.e. Very Low

5. S2 writes O3 = Integrity level of O3 is min(i(S2), i(O3)) which is i(O3) i.e. Very Low