What do Heartbleed, WannaCry, and million dollar iPhone bugs have in common? From a report: One bug affects iPhones, another affects Windows, and the third affects servers running Linux. At first glance these might seem unrelated, but in reality all three were made possible because the software that was being exploited was written in programming languages which allow a category of errors called “memory unsafety.” By allowing these types of vulnerabilities, languages such as C and C++ have facilitated a nearly unending stream of critical computer security vulnerabilities for years.
Imagine you had a program with a list of 10 numbers. What should happen if you asked the list for its 11th element? Most of us would say an error of some sort should occur, and in a memory safe programming language (for example, Python or Java) that’s what would happen. In a memory unsafe programming language, it’ll look at wherever in memory the 11th element would be (if it existed) and try to access it. Sometimes this will result in a crash, but in many cases you get whatever happens to be at that location in memory, even if that portion of memory has nothing to do with our list. This type of vulnerability is called a “buffer-overflow,” and it’s one of the most common types of memory unsafety vulnerabilities. HeartBleed, which impacted 17 percent of the secure web servers on the internet, was a buffer-overflow exploit, letting you read 60 kilobytes past the end of a list, including passwords and other users’ data.
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