ну раз мы заговорили о площадках CTF :

• Hack.me · The house of rising sandbox

• HAX.TOR :: Hacking Challenges - Free Shell Account - Security

• Pwnable.tw

• Reversing.Kr

• Home - CTFlearn - CTF Practice - CTF Problems - CTF Challenges

• CSAW 365

• picoCTF - CMU Cybersecurity Competition

• W3Challs

• Hacking Training For The Best

• Capture The Flag At UCF

• The Cryptopals Crypto Challenges

• https://tryhackme.com/

• Exploit Education :: Andrew Griffiths' Exploit Education

• http://freehackquest.com/

• https://www.root-me.org/

• https://www.vulnhub.com/

• https://ctf.hacker101.com/

• http://ctf.komodosec.com/

• https://attackdefense.com/

• https://cmdchallenge.com/

• https://immersivelabs.com/

• http://www.hackthissite.org/

• http://ctf.infosecinstitute.com/

• https://www.hacking-lab.com/

• https://captf.com/practice-ctf/

• https://www.hacksplaining.com/

• https://junior.stillhackinganyway.nl/

• https://academy.hackaflag.com.br/

• forkbomb