Geoffrey Goodell ?????: > On Sat, Apr 05, 2008 at 02:01:29PM +0400, .FUF wrote: >> Firefox sends your uptime in "gmt_unix_time" field (seconds since boot). >> Other browsers (IE, Opera) send your current system time in UNIX format. > > Even sending the current system time is somewhat troublesome, since > small inaccuracies may be likely to remain relatively constant over long > periods, allowing an attacker to observe, for example, which machine is > twenty seconds slow. Not sure about to what extent running NTP > ameliorates this. > > Geoff > >
Yes, but running NTP syncs can transform this attack to "end-to-end confirmation" attack. Attacker can modify NTP packets (they are being sent over UDP) to hijack your current time (e.g. move it +12 seconds forward) and then correlate HTTPS traffic from anonymous network (or HTTP traffic from hidden service by looking at "Date:" field in HTTP response).
