On 12/05/2016 02:56 PM, sivmu wrote:
Am 04.12.2016 um 05:37 schrieb Maxwell Anselm via arch-general:
You mean the source files that you downloaded and then hashed...
Yes. If the source files are being modified via a MITM attack (which is trivial if the host uses HTTP) the checksum is still useful.
The checksum that was created by zou after downloading the compromised source file.
I don't see how that is useful. The checksum will always be correct and validate nothing
Possibilities 1) MITM attack between end-user and internet. PKGBUILD is downloaded over HTTPS, but source files are downloaded over HTTP. MITM attack cannot manipulate the PKGBUILD, but can fake the sources. AUR maintainer was probably not under the same MITM. ;) 2) Source website hacked. AUR maintainer blindly generates checksums from the compromised source, nothing else matters because everyone is screwed. 3) Source website hacked, after the AUR maintainer generates checksums from the original uncompromised source. ... In cases #1 & #3 (and #3 is only by accident) stronger checksums *will* help. Those are also the cases where it is more likely the maintainer is security-conscious and checks the sources before generating the manually-upgraded-to-sha256-or-higher checksums. ... Context is everything. I am sure many people who read this thread are not aware of the following forum thread in which the matter was extensively discussed: https://bbs.archlinux.org/viewtopic.php?id=217588 Allan has already declared that he will not change the default makepkg.conf, on the grounds that #2 is the most likely scenario for people getting malicious packages. He also wants everyone to know that updpkgsums and makepkg are perfectly okay with maintainers changing the defaults, people who don't know there are defaults to change are probably not your best bet security-wise, and the only real security is either PGP or strong checksums posted by upstream on a second website. Also, that changing the defaults will encourage a false sense of security when people think that checksums have any validity in authentication. Personally, I want the defaults changed because of #1 & #3, but it doesn't seem that will happen *as a matter of principle* so I guess everyone can continue bikeshedding here. Or in arch-dev-public. (Though having a TU take up the fight is indeed somewhat more useful than random users, so who knows?) -- Eli Schwartz