In the past few days several Brazilian ISPs have fallen victim to a series of DNS cache poisoning attacks. These attacks see users being redirected to install malware before connecting to popular sites. Some incidents have also featured attacks on network devices, where routers or modems are compromised remotely.
Brazil has some big ISPs. Official statistics suggest the country has 73 million computers connected to the Internet, and the major ISPs average 3 or 4 million customers each. If a cybercriminal can change the DNS cache in just one server, the number of potential victims is huge.
Last week Brazil’s web forums were alive with desperate cries for help from users who faced malicious redirections when trying to access websites such as YouTube, Gmail and Hotmail, as well as local market leaders including Uol, Terra and Globo. In all cases, users were asked to run a malicious file as soon as the website opened — via redwolf.newsvine.com