Hello, readers! Today I bring you two posts about law: one Mozilla-related, one not. This is the Mozilla-related post. Mozillians may already know this background, but I’ll review for those who don’t.

The “hack”

In 2010 Goatse Security (don’t look them up) discovered a flaw in AT&T’s website. AT&T’s site detected accesses from iPads, extracted a unique account number sent by the iPad, then replied with a private account email address. Account numbers were guessable, so if someone “spoofed” their UA to look like the iPad browser, they could harvest private email addresses using their guesses.

The lulz

The people who figured this out were classic Internet trolls interested (to a degree) in minor mayhem (“lulz”) because they could, and they scraped 114000+ email addresses. Eventually Andrew Auernheimer (known online as “weev”) sent the list to Gawker for an exclusive.

The sky is falling!

AT&T, Apple, the people whose addresses had been scraped, and/or the government panicked and freaked out. The government argued that Auernheimer violated the Computer Fraud and Abuse Act, “exceeding authorized access” by UA-spoofing and loading pages using guessed account numbers.

This is a broad interpretation of “authorized access”. Auernheimer evaded no security measures, only accessed public, non-login-protected pages using common techniques. Anyone who could guess the address could view those pages using common browser addons. People guess at the existence of web addresses all the time. This site’s addresses appear of the form “/year/month/day/post-title/”. The monthly archive links to the side on my site have the form “/year/month/”. It’s a good guess that changing these components does what you expect: no dastardly hacking skills required, just logical guesses and experimentation. And automation’s hardly nefarious.

So what’s Mozilla’s brief with this?

Developers UA-spoof all the time for a variety of innocuous reasons. Newspapers have UA-spoofed during online price discrimination investigations. If UA spoofing is a crime, many people not out for lulz are in trouble, subject to a federal attorney’s whims.

The same is true for constructing addresses by modifying embedded numbers. I’ve provided one example. Jesse once wrote a generic implementation of the technique. Wikipedia uses these tactics internally, for example in the Supreme Court infobox template to linkify docket numbers.

Mozilla thus signed onto an amicus brief in the case. The brief laid out the reasons why the actions the government considered criminal, were “commonplace, legitimate techniques”.

The cool part of the brief

I read the brief last summer through one of Auernheimer’s attorneys at the inestimable Volokh Conspiracy. I’ve been lightly meaning to blog about this discussion of number-changing ever since:

Changing the value of X in the AT&T webpage address is trivial to do. For example, to visit this Court’s homepage, one might type the address “http://www.ca3.uscourts.gov/” into the address bar of the browser window. The browser sends an HTTP request to the Court website, which will respond with this Court’s homepage. Changing the “3” to “4” by typing in the browser window address bar returns the Court of Appeals for the Fourth Circuit’s homepage. Changing the “3” to a “12” returns an error message.

Illustrating the number-guessing technique (and implying its limitations in the “12” part) via the circuit courts’ own websites? Brilliant.

Back to Auernheimer

The court recently threw out Auernheimer’s conviction. Not on CFAA grounds — on more esoteric matters of filing the case in the wrong court. But the opinion contains dicta implying that breaching a password gate or code-based barrier may be necessary to achieve a conviction. The government could bring the case in the right court, but with the implied warning here, it seems risky.

Sympathy

Auernheimer isn’t necessarily a sympathetic defendant. It’s arguably impolite and discourteous to publicly disclose a site vulnerability without giving the site notice and time to fix the issue. It may be “hard to feel sorry for them being handed federal criminal charges” as Ars Technica suggested.

But that doesn’t mean he committed a crime or shouldn’t be defended for doing things web developers often do. Justice means defending people who have broken no laws, when they are threatened with prosecution. It doesn’t mean failing to defend someone just because you don’t like his (legal) actions. Prosecution here was wrong.

One final note

I heard about the AT&T issue and the brief outside Mozilla. I’m unsure what Mozilla channel I should have followed, to observe or discuss the decision to sign onto this brief. Mozilla was right to sign on here. But our input processes for that decision could be better.