On Thu, 06 Jul 2006 16:46:40 -0400, Daniel Serpell wrote: > Hi! > > El Thu, Jul 06, 2006 at 03:18:14PM +0800, James Lau escribio: >> My program is a utility for internet payment. It takes an important role >> in the payment process to ensure security. One of the key functions is >> that the program should detect which machine is paying. So while virtual >> machine (like QEMU) is present, it can cheat the program. Checking the >> hard disk model, cpu type, and other hardward informations makes little >> sense. Because the users or the hackers can easily modify these >> informations. So I need a QEMU internal checking method that hackers >> can't easily bypass. >> >> > Well, as others have argued, this is probably worthless. > > But there is a way to detect virtual machines under x86, see > http://invisiblethings.org/papers/redpill.html
This is an utterly silly way of doing this. For starters, it depends on your OS and where the monitor hides itself. There is no reason the monitor couldn't choose a lower address (assuming user-mode emulation). Also, it's totally useless when QEMU is doing full emulation (or if hardware virtualization is present). The only general way of doing this is to exploit timing differences between the host and guest. Pioneer[1] is a good example of this although it only works on non-VT/SVM systems. If you were exhaustive about timing all possible exits, you could extend this to a VT/SVM system. If hardware is available, static or dynamic attestation also addresses this problem. [1] http://portal.acm.org/affiliated/citation.cfm?id=1095810.1095812&coll=ACM&dl=ACM&type=series&idx=1095810&part=Proceedings&WantType=Proceedings&title=ACM%20Symposium%20on%20Operating%20Systems%20Principles&CFID=15151515&CFTOKEN=6184618 Regards, Anthony Liguori > But if you run qemu without direct instruction copying, it won't work (and > qemu will run slower), because qemu will correctly emulate the > unprivileged instructions. > > Daniel. _______________________________________________ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
