問59
頻出度★★★
迷惑メールを受信したときに避けるべき行動はどれか。
平成23年度 秋期 ITパスポート試験 問59
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 59
Incorrectア
Wrong (i.e., not an action to avoid). Identifying the sender's provider from the routing information in the email header (Received, etc.) and reporting it to that provider's contact desk is a legitimate response that is recommended. The provider can treat it as a violation of its terms of use and take measures such as suspending the sender's account, which helps stop the damage from spreading. Because you do not contact the sender in person, there is also no risk of letting them learn that your address is valid.
- イ
正解 The correct answer is イ. Most spam email is sent out indiscriminately to addresses that were generated mechanically in bulk or harvested from mailing lists, so the sender does not know which addresses are actually in use. If you reply here — even to lodge a complaint — you hand the sender the information that “this address exists and a person is reading it”, the address is then treated as a valid one on their list, and afterwards you may receive even more spam or have your address sold on to other operators. In addition, the source address of spam is often spoofed (impersonated) or disposable, so a reply never reaches a legitimate party and has no effect as a complaint. Replying is therefore the action that should most be avoided.
Incorrectウ
Wrong (i.e., not an action to avoid). Deleting spam without opening it is the safest and most basic response. If you open the body, loading an embedded image can notify the sender through a web beacon that the mail was opened (i.e., that the address is valid), and an attachment or a link can infect you with malware. That is why “do not open it, do not click links, delete it” is the standard practice.
Incorrectエ
Wrong (i.e., not an action to avoid). Setting up the spam filter of your email software so that subsequent mail from the same sender is automatically sorted into the spam folder is an appropriate self-protection measure that is completed entirely on the receiving side. It returns no information at all to the sender while reducing how often such mail reaches your eyes, so it is one of the recommended countermeasures.
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- Never reply to spam — replying, opening the message, and clicking an unsubscribe link all tell the sender that the address exists and is active, which invites more spam and the resale of the address. The source address is often spoofed, so a reply does not work as a complaint either.
- The correct way to deal with spam is through measures that give the sender no response at all and are carried out on the receiving side or via a third party: delete it without opening it, sort it out with a spam filter, and report it to the sender's provider identified from the routing information or to a consultation desk.
用語