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I often see the claim that curl|bash is no worse than what a package manager does. That is simply untrue, for the following reasons. (1) HTTP (no S) MITM. At

I often see the claim that curl|bash is no worse than what a package manager does. That is simply untrue, for the following reasons. (1) HTTP (no S) MITM. At least the lazy devs admit this one. (2) No key/signature checking at all. Sure, some semi-lazy devs will tell you to add their own repo, and maybe you don't check the key for that repo yourself, but there are others who do and they'll raise an alarm you might hear. With curl|bash you don't even get this kind of herd immunity. (3) No dependency checking. (4) No adherence to standards. If you've ever tried to get a package included in e.g. Fedora or Debian, you know that there are people who will go over them with a fine-tooth comb and will reject them if they do bad things (or do them in a bad way). (5) Most install scripts don't handle interrupted downloads well unless the author has taken special care (thank you for this one eridius). If you're piping directly into the shell you have no idea whether that's the case, and if the dev's lazy enough to be doing things this way in the first place the odds are poor. Packages and package repos can be deployed and used in many ways. Some ways provide pretty strong safeguards and guarantees; other ways are weaker. Curl|bash is weaker than any of them. There's just no excuse.

RijilV 10y ago
Indeed, I think most of the harms of curl | bash fall under operational rather than security. To add to your list: 6) reproducibility: vendors could version the download links but I've not seen that done, so you're always getting the latest version which depending on what you're doing might not be what you want. 7) uninstall: maybe the vendor was nice enough to include an install script? Sure with deb/rpm a vendor can screw up the uninstall but the framework is there for them to do it right, with curl | bash the vendor needs to understand that's something they need to do and implement a solution on their own. 8) am I really running bash? And the version you expect me to be? Hopefully your distro isn't evil, but I have more than once found bash just a sym link to something less feature rich. Same goes with older versions, you'd be surprised what features are "new" I also find it a bit odd because the cranky old sysadmin who solves everything with unintelligible shell scripts is often made a mockery of in this world of saltstack, docker, cloud and other buzzwords - yet now we're just signing up for an even worse version of it?
seanp2k2 10y ago
(1) you can easily see and just not use it (2) is incorrect, see https://rvm.io https://rvm.io -- it verifies the script (3) you can do within the script, though you'd have to handle different package managers (4) is true for packages as well. You can put whatever you'd like in an RPM or deb including e.g. A post-install hook to sudo rm -rf --no-preserve-root / Making packages is hard if you want to support many distros. Maybe we should adopt the Go model and just ship binaries.
- Rapzid 10y ago
  Underneath the curl|bash method, which is what is being discussed I believe, there is a link to a "more secure installation.": https://rvm.io/rvm/security https://rvm.io/rvm/security . These instructions have you download and verify a signed installer.

RijilV 10y ago

Indeed, I think most of the harms of curl | bash fall under operational rather than security. To add to your list: 6) reproducibility: vendors could version the download links but I've not seen that done, so you're always getting the latest version which depending on what you're doing might not be what you want. 7) uninstall: maybe the vendor was nice enough to include an install script? Sure with deb/rpm a vendor can screw up the uninstall but the framework is there for them to do it right, with curl | bash the vendor needs to understand that's something they need to do and implement a solution on their own. 8) am I really running bash? And the version you expect me to be? Hopefully your distro isn't evil, but I have more than once found bash just a sym link to something less feature rich. Same goes with older versions, you'd be surprised what features are "new" I also find it a bit odd because the cranky old sysadmin who solves everything with unintelligible shell scripts is often made a mockery of in this world of saltstack, docker, cloud and other buzzwords - yet now we're just signing up for an even worse version of it?

seanp2k2 10y ago

(1) you can easily see and just not use it (2) is incorrect, see https://rvm.io https://rvm.io -- it verifies the script (3) you can do within the script, though you'd have to handle different package managers (4) is true for packages as well. You can put whatever you'd like in an RPM or deb including e.g. A post-install hook to sudo rm -rf --no-preserve-root / Making packages is hard if you want to support many distros. Maybe we should adopt the Go model and just ship binaries.

Rapzid 10y ago
Underneath the curl|bash method, which is what is being discussed I believe, there is a link to a "more secure installation.": https://rvm.io/rvm/security https://rvm.io/rvm/security . These instructions have you download and verify a signed installer.