I’ve been threatening to do a series on “data science community security” for a while and had cause to issue this inaugural post today. It all started with this:
Hey #rstats folks: don't do this. Srsly. Don't do this. Pls. Will blog why. Just don't do this. https://t.co/qkem5ruEBi
― boB Rudis ( @hrbrmstr ) February 23, 2017Let me begin with the following: @henrikbengtsson is an awesome member of the #rstats community. He makes great things and I trust his code and intentions. This post is not about him, it’s about raising awareness regarding security in the data science community.
I can totally see why folks would like Henrik’s tool. Package dependency management ― including installing packages ― is not the most beloved of R tasks, especially for new R users or those who prefer performing their respective science or statistical work vs delve deep into the innards of R. The suggestion to use:
source('http://callr.org/install#knitr')no doubt came from a realization of how cumbersome it can be to deal with said dependency management. You can even ostensibly see what the script does since Henrik provides a link to it right on the page.
So, why the call to not use it?
For starters, if you do want to use this approach, grab his script and make a local copy of it. Read it. Try to grok what it does. Then, use it locally. It will likely be a time-/effort-saver for many R users.
My call was to not source it from the internet.
Why? To answer that I need to talk about trust.
hrbrmstr’s Hierarchy of Package TrustWhen you install a package on your system you’re bringing someone else’s code into your personal work space. When you try to use said code with a library() call, R has a few mechanisms to run code on package startup. So, when you just install and load a package you’re executing real code in the context of your local user. Some of that code may be interpreted R code. Some may be calling compiled code. Some of it may be trying to execute binaries (apps) that are already on your system.
Stop and think about that for a second.
If you saw a USB stick outside your office with a label “Cool/Useful R Package” would you insert it into your system and install the package? (Please tell me you answered “No!” :-)
With that in mind, I have a personal “HieraRchy of Package Trust” that I try to stick by:
Tier 1
This should be a pretty obvious one, but if it’s my own code/server or my org’s code/server there’s inherent trust.
Tier 2When you type install.pacakges() and rely on a known CRAN mirror, MRAN server or Bioconductor download using https you’re getting quite a bit in the exchange.
CRAN GuaRdians at least took some time to review the package. They won’t catch every possible potentially malicious bit and the efficacy of evaluating statistical outcomes is also left to the package user. What you’re getting ― at least from the main cran.r-project.org repo and RStudio’s repos ― are reviewed packages served from decently secured systems run by organizations with good intentions. Your trust in other mirror servers is up to you but there are no guarantees of security on them. I’ve evaluated the main CRAN and RStudio setups (remotely) and am comfortable with them but I also use my own personal, internal CRAN mirror for many reasons, including security.
Revolution-cum-Microsoft MRAN is also pretty trustworthy, especially since Microsoft has quite a bit to lose if there are security issues there.
Bioconductor also has solid package management practices in place, but I don’t use that ecosystem much (at all, really) so can’t speak too much more about it except that I’m comfortable enough with it to put it with the others at that level.
Tier 3If I’m part of a known R cabal in private collaboration, I also trust it, but it’s still raw source and I have to scan through code to ensure the efficacy of it, so it’s a bit further down the list.
Tier 4If I know the contributors to a public source repo, I’ll also consider trusting it, but I will still need to read through the source and doubly-so if there is compiled code involved.
Tiers 5 & 6If the repo source is a new/out-of-the-blue contributor to the R community or hosted personally, it will be relegated to the “check back later” task list and definitely not installed without a thorough reading of the source.
NOTEThere are caveats to the list above ― like CRAN R packages that download pre-compiled windows libraries from GitHub ― that I’ll go into in other posts, along with a demonstration of the perils of trust that I hope doesn’t get Hadley too upset (you’ll see why in said future post :grinning:).
Also note that there is no place on said hierarchy for the random USB stick of cool/useful R code. #justdontdoit
Watering HolesThe places where folks come together to collaborate have a colloquial security name: a “watering hole”. Attackers use these known places to perform ―you guessed it ― “watering hole” attacks. They figure out where you go, who/what you trust and use that to do bad things. I personally don’t know of any current source-code attacks, but data scientists are being targeted in other ways by attackers. If attackers sense there is a source code soft-spot it will only be a matter of time before they begin to use that vector for attack. The next section mentions one possible attacker that you’re likely not thinking of as an “attacker”.
This isn’t FUD .
Governments, competitors and criminals know that the keys to the 21st century economy (for a while, anyway) reside in data and with those who can gather, analyze and derive insight from data. Not all of us have to worry about this, but many of us do and you should not dismiss the value of the work you’re doing, especially if you’re not performing open research. Imagine if a tiny bit of data exfiltration code managed to get on your Spark cluster or even your own laptop. This can easily happen with a tampered package (remember the incident a few years ago with usage tracking code in R scripts?).
A Bit More On httpsI glossed over the https bit above, but by downloading a package over SSL/TLS you’re ensuring that the bits of code aren’t modified in transit from the server to your system and what you’re downloading is also not shown to prying eyes. That’s important since you really want to be sure you’re getting what you think your getting (i.e. no bits are changed) and you may be working in areas your oppressive, authoritarian government doesn’t approve of, such as protecting the environment or tracking global climate change (:tangerine:).
The use of https also does show ―at least in a limited sense ― that the maintainers of the server knew enough to actually setup SSL/TLS and thought ―at leas