Security experts warn that several Brazilian ISPs are under attack after a large number of their subscribers were exposed to various malware attacks when visiting Gmail, Hotmail, and also other trusted websites.
The attackers poisoned the cache of the domain name system, which ISPs use to translate domain names into Internet protocol numbers.
This process ultimately affects end users who are directed to some other website which is capable of exploiting software vulnerabilities and trick the user into installing various malware programs..
A researcher with Kaspersky Labs, Fabio Assoloni, on a blog post, stated, "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," published at Secure List.
Assolini also stated, "In all cases, users were asked to run a malicious file as soon as the website opened."
In most of the cases, the malware pushed into the compromised system is a Trojan which steals various online banking credentials and other sensitive information.