Details Of How The DC Online Voting System Was Hacked:
Small Vulnerability, Huge Consequences from the validate,-validate,-validate dept
We already wrote about the news that some folks at the University of Michigan had successfully hacked
an online voting trial in DC, and suggested that Alex Halderman was the guy behind it (though, he was not identified in the press). Halderman has now written a blog post noting that, indeed, it was him and a few others, and providing a pretty thorough explanation of what happened. The DC project had called on anyone to try to hack it during an open hack period, though they only gave three days notice. Still, it didn’t take long for Halderman, two PhD. students and a member of UMich’s technical staff to find a vulnerability:
The problem, which geeks classify as a “shell-injection vulnerability,” has to do with the ballot upload procedure. When a voter follows the instructions and uploads a completed ballot as a PDF file, the server saves it as a temporary file and encrypts it using a command-line tool called GnuPG. Internally, the server executes the command gpg with the name of this temporary file as a parameter: gpg […] /tmp/stream,28957,0.pdf.