Messages in this thread | | | From | Luke Dashjr <> | Subject | Bug? Non-privileged processes can in some cases spoof the wrong sending IP | Date | Tue, 3 Mar 2020 23:03:35 +0000 |
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It seems non-privileged processes can bind an IP on one interface, and then send to addresses not routed through that interface, to spoof that IP on an unrelated network (eg, the default route).
Shouldn't there be something to prevent this? Presumably it's not expected behaviour, since you can't just bind to any arbitrary addresses...?
(FWIW I can see cases where this might be considered a security issue, but the MAINTAINERS file explicitly said address leaks don't count...)
Luke
P.S. I discovered this because Chromium's WebRTC implementation attempts to send UDP from configured IPv4 address; and then Linux's MASQUERADE also doesn't check that it have the correct return path, so it tried to NAT my WAN to my WAN, which resulted in sending out from the origin IP instead of my own, and triggered my modem to disconnect me. (I guess this scenario is a bit too convoluted to be considered a general DoS risk)
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