問62
頻出度★★★
ランサムウェアの説明として, 適切なものはどれか。
平成25年度 春期 ITパスポート試験 問62
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 62
Incorrectア
This is a description of security software (antivirus software), not of ransomware. What choice ア describes is software on the defending side: software that detects viruses and other threats, protects the computer from threats, and enhances its security. Ransomware, by contrast, is on the side that gets detected and removed; it is malware on the attacking side, so the two stand in exactly opposite positions. Installing security software and keeping its virus definition files (pattern files) up to date is an effective countermeasure against ransomware, but the two must not be mistaken for each other.
- イ
正解 The correct answer is イ. Ransomware is a word made by combining ransom, meaning money demanded for release, with software. It is a kind of malware, that is, a malicious program that harms computers. Once it infects a machine, it encrypts files on the device such as documents, images, and business data one after another without the user’s permission, or locks the screen, leaving the data in a state where it cannot be accessed normally. It then displays a threatening message on the screen and demands payment of money (a ransom) in exchange for the key needed to restore (decrypt) the original state. Choice イ, which reads “software that, once it infects a computer, arbitrarily encrypts files or data so that the data cannot be accessed normally, and demands a ransom from the user to restore it”, states exactly these two characteristics: (1) making data inaccessible through unauthorized encryption, and (2) demanding money in return for recovery. It is therefore an appropriate description of ransomware. Note that paying does not guarantee that the data will be decrypted, so as a rule you should not pay; taking backups routinely and keeping those backups separated from the infected device (offline) is the most effective preparation.
Incorrectウ
This is a description of an OS (operating system, or basic software), not of ransomware. The OS is what controls input/output functions such as keyboard input and screen output, manages disks and memory, manages processes and files, and thereby manages the whole computer system and provides a common foundation for application software. Windows, macOS, Linux, and Android are representative examples; their role is to let users and application programs work without having to deal with the hardware directly. This is a completely different category of software from a malicious program that demands money.
Incorrectエ
This is a description of an IME (Japanese input method, kana-kanji conversion software), not of ransomware. The role of an IME is to assist Japanese text input by converting Roman-letter input into hiragana or katakana, or converting kana into kanji. It is a convenient application program that helps the user with typing; it does not perform malicious actions such as encrypting data and holding it hostage. Note as well that a malicious program that steals the characters you type is called a keylogger, which is likewise a different thing from an IME — worth learning together.
ここがポイント
- Ransomware is a kind of malware whose name comes from ransom, and the core of its definition is a two-stage pattern: (1) it arbitrarily encrypts files or data on the infected device (or locks the screen) so that they cannot be accessed, and (2) it demands money in exchange for restoring them. Since paying does not guarantee recovery, the basic countermeasures are taking regular backups and keeping them offline (in a place disconnected from the network), updating the OS and software, and not opening attachments or links in suspicious e-mails.
- This question asks not about terms with similar names but about whether you can tell apart the categories of software themselves. Choice ア describes security software (the defending side), ウ describes an OS (basic software), and エ describes an IME (Japanese input method), while malware differs from all three: it is a general term for malicious programs whose purpose is to cause harm to users. Besides ransomware, malware includes computer viruses that attach to other files and multiply, worms that reproduce themselves on their own, Trojan horses that intrude by disguising themselves as legitimate software, spyware that sends information to the outside, and keyloggers that record keystrokes; each is identified by its characteristic behavior.
用語