問100
頻出度★★★
正しいURLを指定してインターネット上のWebサイトへアクセスしようとした利用者が，偽装されたWebサイトに接続されてしまうようになった。原因を調べたところ，ドメイン名とIPアドレスの対応付けを管理するサーバに脆弱性があり，攻撃者によって，ドメイン名とIPアドレスを対応付ける情報が書き換えられていた。このサーバが受けた攻撃はどれか。
令和6年度 ITパスポート試験 問100
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 100
Incorrectア
A DDoS attack sends a huge volume of traffic from many devices to overload a target server or network, causing it to stop or slow down — an attack on availability. Its purpose is to make a service unusable, which is unrelated to the phenomenon in this question, where the mapping information is rewritten to redirect users to a forged site.
- イ
正解 The correct answer is “イ”, DNS Cache Poisoning. A DNS server manages the mapping between domain names and IP addresses (name resolution); the attack that exploits its vulnerability to rewrite the mapping information (the cache) with illegitimate values is DNS Cache Poisoning. Once it is rewritten, even if the user enters the correct URL, they are directed to a wrong IP address and end up connected to a forged site prepared by the attacker. This matches the situation in the question, where the information mapping domain names to IP addresses had been rewritten.
Incorrectウ
Social engineering is a technique that exploits gaps in people's psychology or behavior to extract passwords or confidential information through impersonation phone calls, shoulder surfing, dumpster diving, and the like. It differs in nature from the attack in this question, which technically rewrites the server's mapping information.
Incorrectエ
A drive-by download is an attack in which merely viewing a website causes malicious programs to be automatically downloaded and infect the device without the user noticing. Its goal is to infect the browsing device with malware, which is different from rewriting the mapping information on a DNS server.
ここがポイント
- DNS Cache Poisoning is an attack that exploits a vulnerability in a DNS server to tamper with the mapping information (the cache) between domain names and IP addresses, directing users who entered the correct URL to a forged site.
- Distinguish the aim of each attack: DDoS disrupts availability, social engineering extracts information through people, and a drive-by download automatically infects with malware during browsing.
用語