Cybercriminals are constantly on the lookout for means and methods to make attacks more destructive. In Q4 2020, Citrix ADC (application delivery controller) devices became one such tool, when perpetrators abused their DTLS interface. The DTLS (Datagram Transport Layer Security) protocol is used to establish secure connections over UDP, through which most DNS queries, as well as audio and video traffic, are sent. To amplify the attack, the attackers sent requests to devices with the DTLS interface enabled, spoofing victims’ IP addresses. Consequently, the victims received reply packets several times larger in size.
In the case of Citrix devices, the amount of junk traffic could increase by up to 36 times. After the attacks came to light, the manufacturer promptly released a firmware update for configuring verification of incoming requests. For those who do not use DTLS, it is recommended to simply disable this protocol.
Another notable attack in December targeted the website Bitcoin.org, which hosts Bitcoin Core, one of the most widely used software versions of bitcoin.
Related story: Spam and phishing in 2020