I'm far from an expert security pentester but I know my basics... and I'm always amazed at how simple these exploits are. Guys, come on, it's 2014, if you're writing C and using strcat/strcpy/sprintf/fprintf/etcetc with non-sanitized input, you're pretty much asking for it.

Even a rookie would spot such mistake and exploit it, it's always among the first obstacles to bypass at local CTFs and it's the #1 exploit that people think about when they think about a "security vulnerability".