Twitter has employed a known hacker to review its security policies. Peiter Zatko, known by his hacker name ‘Mudge’ was hired to tackle issues such as engineering problems and misinformation. He will undergo a 45 to 60-day review to recommend changes. Zatko has previously worked at electronic payments provider Stripe, and also for the Pentagon. The ‘white hat hacker’ will aim to prevent hacks such as those which affected Barack Obama – who was in targeted by ‘bitcoin hackers’.