問90
頻出度★★★
次の情報セキュリティに係る事象において, 機密性, 完全性及び可用性のうち, 損なわれたものだけを全て挙げたものはどれか。 職場のファイルサーバにおいて, サーバ上のファイルを全て暗号化して保存していたが, サーバがウイルスに感染し, 一部のファイルが削除されてしまった。 ウイルスの駆除とファイルの復旧に数時間を要し, その間は業務が行えない状態となり, 利用者に迷惑をかけてしまった。
平成29年度 秋期 ITパスポート試験 問90
テクノロジ系セキュリティ › 情報セキュリティ管理
This question's explanation and your answers so far.
解説
問 90
Incorrectア
This lists only confidentiality, but because the files were stored encrypted and no information leak occurred, confidentiality was actually not compromised. In addition, the integrity and availability that were actually compromised are not listed, so the choice of elements is reversed, making it incorrect.
Incorrectイ
This lists confidentiality and integrity, but confidentiality was not compromised thanks to encryption, and including the confidentiality that was not compromised is incorrect. Also, the availability that was actually compromised by being unable to conduct business for several hours is missing, so the listed elements are not correct.
- ウ
正解 Among the three elements of information security (confidentiality, integrity, and availability), if we list only the ones compromised in this incident, they are integrity and availability, so the correct answer is ウ. First, because all files on the server were stored encrypted, even though the virus infection and file deletion occurred, the contents were not read by a third party and leaked, so confidentiality was not compromised. On the other hand, the virus deleted some files, so data that should have existed was lost and the contents could no longer be kept correct, so integrity was compromised. Furthermore, removing the virus and recovering the files took several hours, during which business operations could not be performed, and the server and files could not be used when needed, so availability was also compromised. Only integrity and availability were compromised, so ウ, which lists only these two, is the correct answer.
Incorrectエ
This lists only availability. While it is correct that availability was compromised, the violation of integrity — data being lost due to file deletion — is left out. Since the question asks to list all of the compromised items, エ, which lacks integrity, is insufficient and incorrect.
ここがポイント
- Definition of the three elements of information security (CIA): confidentiality = only authorized persons can access the information; integrity = information is kept accurate, without tampering or loss; availability = information or systems can be used when needed.
- Judge the incident by mapping it onto the three elements: if there is no leak thanks to encryption, confidentiality is intact; file deletion is a violation of integrity; business stoppage and unavailability are a violation of availability. Separate them this way and choose all and only the items that were compromised.
用語