問58
頻出度★★★
インターネットなどのネットワークを介して，自分自身の複製を電子メールに添付して勝手に送信したり，ネットワーク上のほかのコンピュータに自分自身をコピーしたりして，自己増殖するプログラムはどれか。
平成21年度 秋期 ITパスポート試験 問58
テクノロジ系セキュリティ › 情報セキュリティ
This question's explanation and your answers so far.
解説
問 58
Incorrectア
A cookie is a small piece of data that a web server has the browser store, used to retain user information such as login status or session identification. It is merely data, not a program: it does not run by itself and does not self-replicate. Privacy concerns are sometimes raised about cookies, but they are not malware.
Incorrectイ
Spyware is a program that hides so the user does not notice it, collects information such as keystrokes and browsing history, and sends it outside. Its purpose is stealing information; self-replication — attaching itself to email or copying itself to other computers — is not its essential nature.
Incorrectウ
A Trojan horse is a program that disguises itself as useful software or a harmless file so that users install it themselves, and then performs malicious actions behind the scenes (opening a backdoor, stealing information, and so on). Its route of intrusion depends on the user running it, and it has no ability to travel across a network and multiply on its own — the decisive difference from a worm.
- エ
正解 The correct answer is エ (Worm). A worm is malware that runs on its own without attaching itself to another program, and multiplies by making copies of itself. The behaviors listed in the question — attaching a copy of itself to email and sending it without permission, and copying itself to other computers on the network — are exactly self-propagation over a network, the defining feature of a worm. Because the infection itself involves communication, sending large volumes of email and scanning the network consumes bandwidth and degrades the performance of the whole network, which is a typical form of damage.
ここがポイント
- Definition of a worm: malware that does not attach itself to another program, runs independently, and replicates and spreads itself over a network or by email.
- Comparing categories of malware: a worm self-replicates, a computer virus multiplies by attaching to other files, a Trojan horse disguises itself so the user runs it, and spyware steals information. A cookie is not malware at all — it is just data.
用語