A Princeton University student has shed light on security flaws in Java and .Net virtual machines using a lamp, some known properties of computer memory and a little luck.
An attack requires physical access to the computer, so the technique poses little threat to virtual machines running on PCs and servers. But it could be used to steal data from smart cards, said Sudhakar Govindavajhala, a computer-science graduate student at Princeton who demonstrated the procedure Tuesday.
"There are smart cards that use Java that you could shine a light on, flip a bit and get access to the card's data," he said. Govindavajhala presented the paper at the Institute of Electrical and Electronic Engineers (IEEE) Symposium on Security and Privacy here.
The technique relies on the ability of energy to "flip bits" in memory. While cosmic rays can very occasionally cause a random bit in memory to change value, from 0 to 1 or from 1 to 0, Govindavajhala decided not to wait. He used a lamp to heat up the chips inside a computer and cause one or more bits of memory to change.
By doing so, the researcher broke the security model that virtual machine's rely on--that the computer faithfully executes its instruction set.
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