Access Control Models Assume a network that consists of a set of nodes, {a, b, c, d, e, f, g, h, j, k, l, x, z}. These nodes have the following partial order relation on them: {(b≤a), (f≤e), (z≤l), (z≤x), (l≤g), (c≤b), (g≤k), (e≤d), (g≤h), (k≤j), (g≤e), (e≤c), (d≤b), (x≤e)} Furthermore, assume that a BLP policy is being enforced in the above network. Now assume that at some stage, node z becomes infected with a virus. Which one of the following sets of actions would also lead to infecting node a,
Access Control Models
Assume a network that consists of a set of nodes, {a, b, c, d, e, f, g, h, j, k, l, x, z}. These nodes have
the following partial order relation on them:
{(b≤a), (f≤e), (z≤l), (z≤x), (l≤g), (c≤b), (g≤k), (e≤d), (g≤h), (k≤j), (g≤e), (e≤c), (d≤b), (x≤e)}
Furthermore, assume that a BLP policy is being enforced in the above network. Now assume that at
some stage, node z becomes infected with a virus. Which one of the following sets of actions would
also lead to infecting node a, assuming that viruses propagate through a network using the read and
write commands. A virus would propagate from one node to another either because the second
node read from the first one, or because the first node wrote to the second one. All read and write
commands are subject to the policy being enforced and no read or write operation is possible in the
absence of an order (either direct or indirect) between two nodes:
a) (l read from z), (l write to g), (g read from l), (g read from e), (e write to c), (c write to b), (a
read from b)
b) (z read from l), (a read from l)
c) (z write to x), (x write to e), (a read from e)
d) (z write to c), (b write to c), (a read from b)
e) (z write to g), (g write to h), (b read from h), (b write to a)
f) (x read from z), (x write to e), (e write to d), (a write to d)
g) (z write to g), (j read from g), (j write to d), (d write to b), (a read from b)
h) (z write to l), (l write to g), (g write to c), (c write to d), (d write to b), (b write to a)
i) (a write to z)
j) (f read from z), (a read from f)
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