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Any time you install a package (an RPM, deb, .exe, etc.), including from something like yum or apt-get, you are trusting somebody with root access to your syste

Any time you install a package (an RPM, deb, .exe, etc.), including from something like yum or apt-get, you are trusting somebody with root access to your system, including the ability to run arbitrary shell commands. This is something to take seriously; but not something to dismiss as entirely unacceptable. It is generally a manageable, and somewhat quantifiable, risk. This is no different than if the Rust developers provided an RPM or deb package for you to install; the same privileges are being granted to them. Though it is the same thing, it doesn't seem to generate the same concern as the "pipe this file into a shell" method of installation. In fact, one of the folks who responded to you explained that this problem will be gone once rust is packaged for distribution...but that merely means the commands are different, not that rust developers aren't being granted root access to your system. It is possibly even more suspect, in the case of binary packages, since in the case of the shell script, you could download it, look at it, and then run it. A binary package might have modifications that aren't included in the source distribution, and it would be difficult for a non-expert to spot those differences (and an expert would need to go looking for them, and might miss them). This is why signed packages are a big deal in the free OS world. At least you know who signed off on your package. In short, you're right: It's kind of crazy that people grant root access to arbitrary people every time they install software. But, it's the way things are done, for now, so we deal with it and only install stuff from people we perceive to be trustworthy. (i.e. be careful what apt and yum repositories you enable on your systems, and what scripts you pipe into a sudo shell.)

ajross 12y ago
All of that is true. But when I pull a package on Ubuntu or Fedora, it's checked against a key that came with the the system at install time as part of the whole package authentication infrastructure. The root of trust is rather stronger than running the output of some random unencrypted HTTP URL. And the distros recognize that and publish hash values for their install media in lots of obvious places. This is just a bad habit from the OS X world that needs to die. Really there should be some part of the step that allows a typical user to at least try to manually authenticate the root of trust, via a published hash on a bootstrap package maybe (that's what third party RPM/deb archives do, for example).
- chc 12y ago
  I don't see how comparing an install script you get from somebody with a hash you get from that same somebody gains you an appreciable amount of security. If their server is compromised, you can't trust the hash either. Basically, what you need is a source of trust external to the transaction. If that isn't available and you aren't going to manually review everything, I don't see how this is meaningfully different.
  - ajross 12y ago
    It doesn't give you "perfect" authentication (because nothing does, that's the why the whole root of trust issue is so difficult), but to argue that it isn't appreciably different than literally running the output of curl is just silly. If I don't trust the hash value I got from the Fedora web site I can ask Google. I can check it vs. the mirrors. I can ask my friend who installed it already to see if it matches her file. I can check the signature on the hash to make sure it matches the key I have stored from my existing install (or the one before that, etc...). That's not perfect but at least it's something.
    - chc 12y ago
      Yes, but I'm talking about the case where you do trust the hash value just like people who use this method trust rust-lang.org. If you don't trust this software, you could download it and get a hash from somebody you trust as well — in neither case are you forced to do it the easier and less secure way. Obviously a quick install process where you trust the source will be less secure than a laborious process where you carefully inspect the code or obtain and verify multiple hashes via sneakernet. But I'm not convinced that the "secure" easy path where you get a file from somebody and a hash/key from the same source, see that the two match and then run the file is actually more secure in any meaningful way than piping curl into sh. The difference seems to be more in the user's level of caution — this method just lays what you're doing bare rather than burying it under layers of indirection.
      - ajross 12y ago
foobarqux 12y ago
It's completely wrong to equate the security of installing software via curl+pipe to installing signed packages. There are certainly security holes in first-party signed package installation but they pale in comparison the attack surface of curl+pipe. Systems need to be made more secure and curl+pipe is a step in the wrong direction. It's kind of shocking that attacks are becoming more sophisticated and prevalent but security is becoming more complacent. > only install stuff from people we perceive to be trustworthy. Except you can't authenticate the script with curl+pipe, so if someone compromised the server or the communication link it's game over.
- SwellJoe 12y ago
  I don't believe it is "completely wrong", and I discussed the reason you should prefer signed packages from your OS vendor, though that wasn't my focus. If you install packages from a third party, and if they are signed, you are generally getting the signing key from the same location. i.e. when the rust developers build packages (as has been suggested will be the solution to this problem), you'll also need to install their signing key. Presumably from the same webserver that is serving you the script that is being judged insecure in this thread. "Except you can't authenticate the script with curl+pipe, so if someone compromised the server or the communication link it's game over." s/package and signing key/script with curl+pipe/ The two are not dramatically different if an attacker has taken over the website in question, or if the build/distribution infrastructure has otherwise been compromised, and that was my point. You could do an sha checksum of the script, and you could obtain the package signing key by meeting up with the developer in person and checking their ID, and you could download the sources, check them thoroughly, and build your own packages, etc., etc. Very few people do that. There are levels of risk at every stage. It is a difficult problem to distribute software in a safe fashion. All of that said: I install everything from a package. If it is not from the OS standard repository, I download the source package and build it myself (sometimes checking the source tarball for anomalies and checking the patches to be sure nothing is obviously amiss). I do not enable third party repositories unless I trust them a lot. If no package is available, I make one, and sign it with my own key. If I can't make one, I don't use the software in a deployment (the cost of maintaining a piece of software built from source is way too high). I was not suggesting the curl+pipe is a good practice. Merely that we live in a world full of compromises. And, insuring you are getting what you think you're getting, and that the person who packaged it had no malicious intent, is a lot harder than merely installing from a package (particularly a package from a source that doesn't have stringent identity requirements...Debian and Fedora packages have a pretty clear ownership trail...most third party packages do not).

ajross 12y ago

All of that is true. But when I pull a package on Ubuntu or Fedora, it's checked against a key that came with the the system at install time as part of the whole package authentication infrastructure. The root of trust is rather stronger than running the output of some random unencrypted HTTP URL. And the distros recognize that and publish hash values for their install media in lots of obvious places. This is just a bad habit from the OS X world that needs to die. Really there should be some part of the step that allows a typical user to at least try to manually authenticate the root of trust, via a published hash on a bootstrap package maybe (that's what third party RPM/deb archives do, for example).

chc 12y ago
I don't see how comparing an install script you get from somebody with a hash you get from that same somebody gains you an appreciable amount of security. If their server is compromised, you can't trust the hash either. Basically, what you need is a source of trust external to the transaction. If that isn't available and you aren't going to manually review everything, I don't see how this is meaningfully different.
- ajross 12y ago
  It doesn't give you "perfect" authentication (because nothing does, that's the why the whole root of trust issue is so difficult), but to argue that it isn't appreciably different than literally running the output of curl is just silly. If I don't trust the hash value I got from the Fedora web site I can ask Google. I can check it vs. the mirrors. I can ask my friend who installed it already to see if it matches her file. I can check the signature on the hash to make sure it matches the key I have stored from my existing install (or the one before that, etc...). That's not perfect but at least it's something.
  - chc 12y ago
    Yes, but I'm talking about the case where you do trust the hash value just like people who use this method trust rust-lang.org. If you don't trust this software, you could download it and get a hash from somebody you trust as well — in neither case are you forced to do it the easier and less secure way. Obviously a quick install process where you trust the source will be less secure than a laborious process where you carefully inspect the code or obtain and verify multiple hashes via sneakernet. But I'm not convinced that the "secure" easy path where you get a file from somebody and a hash/key from the same source, see that the two match and then run the file is actually more secure in any meaningful way than piping curl into sh. The difference seems to be more in the user's level of caution — this method just lays what you're doing bare rather than burying it under layers of indirection.
    - ajross 12y ago

foobarqux 12y ago

It's completely wrong to equate the security of installing software via curl+pipe to installing signed packages. There are certainly security holes in first-party signed package installation but they pale in comparison the attack surface of curl+pipe. Systems need to be made more secure and curl+pipe is a step in the wrong direction. It's kind of shocking that attacks are becoming more sophisticated and prevalent but security is becoming more complacent. > only install stuff from people we perceive to be trustworthy. Except you can't authenticate the script with curl+pipe, so if someone compromised the server or the communication link it's game over.

SwellJoe 12y ago
I don't believe it is "completely wrong", and I discussed the reason you should prefer signed packages from your OS vendor, though that wasn't my focus. If you install packages from a third party, and if they are signed, you are generally getting the signing key from the same location. i.e. when the rust developers build packages (as has been suggested will be the solution to this problem), you'll also need to install their signing key. Presumably from the same webserver that is serving you the script that is being judged insecure in this thread. "Except you can't authenticate the script with curl+pipe, so if someone compromised the server or the communication link it's game over." s/package and signing key/script with curl+pipe/ The two are not dramatically different if an attacker has taken over the website in question, or if the build/distribution infrastructure has otherwise been compromised, and that was my point. You could do an sha checksum of the script, and you could obtain the package signing key by meeting up with the developer in person and checking their ID, and you could download the sources, check them thoroughly, and build your own packages, etc., etc. Very few people do that. There are levels of risk at every stage. It is a difficult problem to distribute software in a safe fashion. All of that said: I install everything from a package. If it is not from the OS standard repository, I download the source package and build it myself (sometimes checking the source tarball for anomalies and checking the patches to be sure nothing is obviously amiss). I do not enable third party repositories unless I trust them a lot. If no package is available, I make one, and sign it with my own key. If I can't make one, I don't use the software in a deployment (the cost of maintaining a piece of software built from source is way too high). I was not suggesting the curl+pipe is a good practice. Merely that we live in a world full of compromises. And, insuring you are getting what you think you're getting, and that the person who packaged it had no malicious intent, is a lot harder than merely installing from a package (particularly a package from a source that doesn't have stringent identity requirements...Debian and Fedora packages have a pretty clear ownership trail...most third party packages do not).