問54
頻出度★★★
不正プログラムの一種であるトロイの木馬の特徴はどれか。
平成24年度 春期 ITパスポート試験 問54
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 54
Incorrectア
Infecting data files by exploiting the macro function of application software is a characteristic of a macro virus. It is a virus written in macros (simple programs) that can be embedded in spreadsheet or word-processing documents; it runs when the document file is opened and spreads the infection to other documents. Attaching itself to other files in order to infect them is what makes it different from a Trojan horse, which is self-contained and carries out no infection activity.
Incorrectイ
Spreading false virus information, such as warning messages about new viruses, via chain mail is an act known as a virus hoax (hoax e-mail). It is not a program but merely false information that plays on people's fears to make them forward it, so it is not a malicious program in the first place. Its actual harm is network congestion from the mass forwarding of mail and confusion among users; unlike a Trojan horse, no program runs to cause damage, and that is the decisive difference.
Incorrectウ
Self-propagating by sending copies of itself to other computers over a network is a characteristic of a worm. Like a Trojan horse, a worm does not attach itself to other files and runs on its own, but it has the ability to self-propagate, replicating itself over the network and spreading the infection from one machine to the next. A Trojan horse does not self-propagate; it spreads by making users mistake it for useful software so that they install it themselves, and that is the difference.
- エ
正解 A Trojan horse is a malicious program that takes on the appearance of “useful software” such as a game or a utility so that users install and run it themselves, while behind the scenes it performs malicious actions such as destroying the system, tampering with files, stealing personal information and passwords, and accepting remote control from outside. As its name suggests, it comes from the Greek myth in which a wooden horse hiding soldiers was carried inside the city walls, and its essence is that the user is made to invite it in. Therefore エ, which states that after being distributed disguised as useful software it performs malicious actions such as destroying the system or stealing personal information, is the correct answer. Another important characteristic is that a Trojan horse does not attach itself to (infect) other files and does not multiply by making copies of itself; it works as a self-contained, standalone program. This is why the “infection” in ア and the “self-propagation” in ウ do not apply to a Trojan horse.
ここがポイント
- Definition of a Trojan horse: a malicious program that disguises itself as useful, harmless software so that users install and run it, and then performs malicious actions such as destruction, information theft, and remote control behind the scenes. It neither infects other files nor self-propagates, and it works as a standalone program.
- Organize the types of malware by whether they infect and whether they self-propagate: viruses (including macro viruses) attach to other files and infect them, worms do not attach but do self-propagate, and Trojan horses neither attach nor self-propagate but get in through disguise. Also distinguish virus hoaxes (false information spread by chain mail), which are not even programs.
用語