We Claim:
[Claim I]
A security management apparatus comprising:
a communication unit to exterally receive dependency infrmation indicating a dependence relation among infrmation assets idividually held by a fst system and one or more second systems diferent fom the fst system; and
a selection unit to select a security measure to be implemented fom candidates fr a security measure against a threat to an infrmation asset held by the frst system, in accordance with a dependence relation indicated by the dependency infrmation received by the comunication unit.
[Claim 2]
The security management apparatus according to claim l, wherein the selection unit selects, as a security measure to be implemented, a security measure that is to limit an access source to a frst infrmation asset that is an infrmation asset held by the frst system, to a second system holding a second infrmation asset that is an infrmation asset dependent on the frst infrmation asset.
[Claim 3]
The security management apparatus according to claim 1 or 2, frher compnsmg:
a generation unit to generate a relation tree that is data to defne the dependence relation in a tree strcture, fom the dependency infrmation, wherein
the selection unit refrs to a relation tree generated by the generation unit to specify the dependence relation.

[Claim 4]
The security management apparatus according to any one of claims 1 to 3, wherein
the dependency information includes information indicating an importance of an information asset held by the first system with respect to an information asset of a dependent source,
the security management apparatus further comprises a calculation unit to calculate an evaluation value of the candidates from an importance indicated with the dependency information, and
the selection unit selects a security measure to be implemented in accordance with not only the dependence relation, but also an evaluation value calculated by the calculation unit.
[Claim 5]
The security management apparatus according to any one of claims 1 to 4, further comprising an extraction unit to extract, for each security measure, an index value of each of the candidates from a database storing an index values for selecting a security measure, wherein
the selection unit selects, as a security measure to be implemented, a security measure whose index value extracted by the extraction unit satisfies a condition.
[Claim 6]
The security management apparatus according to claim 5, wherein the communication unit externally receives information indicating the

condition.
[Claim 7]
The security management apparatus according to any one of claims 1 to 6, further comprising a detection unit to detect a change in a configuration of the first system, wherein
the selection unit selects a security measure to be implemented in accordance with not only the dependence relation, but also a change detected by the detection unit.
[Claim 8]
The security management apparatus according to any one of claims 1 to 7, wherein
the security management apparatus is included in the first system, and shares the dependency information with other security management apparatus included in the one or more second systems.
[Claim 9]
A central security management apparatus for aggregating the dependency information from the security management apparatus according to any one of claims 1 to 7 included in the first system, and from other security management apparatus included in the one or more second systems.
[Claim 10]
A security management method comprising:
externally receiving, by a communication unit, dependency information

indicating a dependence relation among information assets individually held by a first system and one or more second systems different from the first system; and
selecting, by a selection unit, a security measure to be implemented from candidates for a security measure against a threat to an information asset held by the first system, in accordance with a dependence relation indicated by the dependency information received by the communication unit.
[Claim 11]
A security management program for causing
a computer to execute:
processing for externally receiving dependency information indicating a dependence relation among information assets individually held by a first system and one or more second systems different from the first system; and
processing for selecting a security measure to be implemented from candidates for a security measure against a threat to an information asset held by the first system, in accordance with a dependence relation indicated by the dependency information.