Last week, researchers disclosed vulnerabilities in a large number of encrypted e-mail clients: specifically, those that use OpenPGP and S/MIME, including Thunderbird and AppleMail. These are serious vulnerabilities: An attacker who can alter mail sent to a vulnerable client can trick that client into sending a copy of the plaintext to a web server controlled by that attacker. The story of these vulnerabilities and the tale of how they were disclosed illustrate some important lessons about security vulnerabilities in general and e-mail security in particular.
But first, if you use PGP or S/MIME to encrypt e-mail, you need to check the list on this page and see if you are vulnerable. If you are, check with the vendor to see if they’ve fixed the vulnerability. (Note that some early patches turned out not to fix the vulnerability.) If not, stop using the encrypted e-mail program entirely until it’s fixed. Or, if you know how to do it, turn off your e-mail client’s ability to process HTML e-mail or — even better — stop decrypting e-mails from within the client. There’s even more complex advice for more sophisticated users, but if you’re one of those, you don’t need me to explain this to you.
Consider your encrypted e-mail insecure until this is fixed.
All software contains security vulnerabilities, and one of the primary ways we all improve our security is by researchers discovering those vulnerabilities and vendors patching them. It’s a weird system: Corporate researchers are motivated by publicity, academic researchers by publication credentials, and just about everyone by individual fame and the small bug-bounties paid by some vendors.
Software vendors, on the other hand, are motivated to fix vulnerabilities by the threat of public disclosure. Without the threat of eventual publication, vendors are likely to ignore researchers and delay patching. This happened a lot in the 1990s, and even today, vendors often use legal tactics to try to block publication. It makes sense; they look bad when their products are pronounced insecure.
Over the past few years, researchers have started to choreograph vulnerability announcements to make a big press splash. Clever names — the e-mail vulnerability is called “Efail” — websites, and cute logos are now common. Key reporters are given advance information about the vulnerabilities. Sometimes advance teasers are released. Vendors are now part of this process, trying to announce their patches at the same time the vulnerabilities are announced.
This simultaneous announcement is best for security. While it’s always possible that some organization — either government or criminal — has independently discovered and is using the vulnerability before the researchers go public, use of the vulnerability is essentially guaranteed after the announcement. The time period between announcement and patching is the most dangerous, and everyone except would-be attackers wants to minimize it.
Things get much more complicated when multiple vendors are involved. In this case, Efail isn’t a vulnerability in a particular product; it’s a vulnerability in a standard that is used in dozens of different products. As such, the researchers had to ensure both that everyone knew about the vulnerability in time to fix it and that no one leaked the vulnerability to the public during that time. As you can imagine, that’s close to impossible.
Efail was discovered sometime last year, and the researchers alerted dozens of different companies between last October and March. Some companies took the news more seriously than others. Most patched. Amazingly, news about the vulnerability didn’t leak until the day before the scheduled announcement date. Two days before the scheduled release, the researchers unveiled a teaser — honestly, a really bad idea — which resulted in details leaking.
After the leak, the Electronic Frontier Foundation posted a notice about the vulnerability without details. The organization has been criticized for its announcement, but I am hard-pressed to find fault with its advice. (Note: I am a board member at EFF.) Then, the researchers published — and lots of press followed.
All of this speaks to the difficulty of coordinating vulnerability disclosure when it involves a large number of companies or — even more problematic — communities without clear ownership. And that’s what we have with OpenPGP. It’s even worse when the bug involves the interaction between different parts of a system. In this case, there’s nothing wrong with PGP or S/MIME in and of themselves. Rather, the vulnerability occurs because of the way many e-mail programs handle encrypted e-mail. GnuPG, an implementation of OpenPGP, decided that the bug wasn’t its fault and did nothing about it. This is arguably true, but irrelevant. They should fix it.
Expect more of these kinds of problems in the future. The Internet is shifting from a set of systems we deliberately use — our phones and computers — to a fully immersive Internet-of-things world that we live in 24/7. And like this e-mail vulnerability, vulnerabilities will emerge through the interactions of different systems. Sometimes it will be obvious who should fix the problem. Sometimes it won’t be. Sometimes it’ll be two secure systems that, when interact in a particular way, cause an insecurity. In April, I wrote about a vulnerability that arose because Google and Netflix make different assumptions about e-mail addresses. I don’t even know who to blame for that one.
It gets even worse. Our system of disclosure and patching assumes that vendors have the expertise and ability to patch their systems, but that simply isn’t true for many of the embedded and low-cost Internet of things software packages. They’re designed at a much lower cost, often by offshore teams that come together, create the software, and then disband; as a result, there simply isn’t anyone left around to receive vulnerability alerts from researchers and write patches. Even worse, many of these devices aren’t patchable at all. Right now, if you own a digital video recorder that’s vulnerable to being recruited for a botnet — remember Mirai from 2016? — the only way to patch it is to throw it away and buy a new one.
Patching is starting to fail, which means that we’re losing the best mechanism we have for improving software security at exactly the same time that software is gaining autonomy and physical agency. Many researchers and organizations, including myself, have proposed government regulations enforcing minimal security-standards for Internet-of-things devices, including standards around vulnerability disclosure and patching. This would be expensive, but it’s hard to see any other viable alternative.
Getting back to e-mail, the truth is that it’s incredibly difficult to secure well. Not because the cryptography is hard, but because we expect e-mail to do so many things. We use it for correspondence, for conversations, for scheduling, and for record-keeping. I regularly search my 20-year e-mail archive. The PGP and S/MIME security protocols are outdated, needlessly complicated and have been difficult to properly use the whole time. If we could start again, we would design something better and more user friendlybut the huge number of legacy applications that use the existing standards mean that we can’t. I tell people that if they want to communicate securely with someone, to use one of the secure messaging systems: Signal, Off-the-Record, or — if having one of those two on your system is itself suspicious — WhatsApp. Of course they’re not perfect, as last week’s announcement of a vulnerability (patched within hours) in Signal illustrates. And they’re not as flexible as e-mail, but that makes them easier to secure.
This essay previously appeared on Lawfare.com.
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Last week, the Department of Justice released 18 new FISC opinions related to Section 702 as part of an EFF FOIA lawsuit. (Of course, they don’t mention EFF or the lawsuit. They make it sound as if it was their idea.)
There’s probably a lot in these opinions. In one Kafkaesque ruling, a defendant was denied access to the previous court rulings that were used by the court to decide against it:
…in 2014, the Foreign Intelligence Surveillance Court (FISC) rejected a service provider’s request to obtain other FISC opinions that government attorneys had cited and relied on in court filings seeking to compel the provider’s cooperation.
The provider’s request came up amid legal briefing by both it and the DOJ concerning its challenge to a 702 order. After the DOJ cited two earlier FISC opinions that were not public at the time — one from 2014 and another from 2008 — the provider asked the court for access to those rulings.
The provider argued that without being able to review the previous FISC rulings, it could not fully understand the court’s earlier decisions, much less effectively respond to DOJ’s argument. The provider also argued that because attorneys with Top Secret security clearances represented it, they could review the rulings without posing a risk to national security.
The court disagreed in several respects. It found that the court’s rules and Section 702 prohibited the documents release. It also rejected the provider’s claim that the Constitution’s Due Process Clause entitled it to the documents.
This kind of government secrecy is toxic to democracy. National security is important, but we will not survive if we become a country of secret court orders based on secret interpretations of secret law.
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The password-manager 1Password has just implemented a travel mode that tries to protect users while crossing borders. It doesn’t make much sense. To enable it, you have to create a list of passwords you feel safe traveling with, and then you can turn on the mode that only gives you access to those passwords. But since you can turn it off at will, a border official can just demand you do so. Better would be some sort of time lock where you are unable to turn it off at the border.
There are a bunch of tricks you can use to ensure that you are unable to decrypt your devices, even if someone demands that you do. Back in 2009, I described such a scheme, and mentioned some other tricks the year before. Here’s more. They work with any password manager, including my own Password Safe.
There’s a problem, though. Everything you do along these lines is problematic, because 1) you don’t want to ever lie to a customs official, and 2) any steps you take to make your data inaccessible is in itself suspicious. Your best defense is not to have anything incriminating on your computer or in the various social media accounts you use. (This advice was given to Australian citizens by their Department of Immigration and Border Protection specifically to Muslims pilgrims returning from hajj. Bizarrely, an Australian MP complained when Muslims repeated that advice.)
The EFF has a comprehensive guide to both the tech and policy of securing your electronics for border crossings.
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Interesting post on Cloudflare’s experience with receiving a National Security Letter.
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For years, the DMCA has been used to stifle legitimate research into the security of embedded systems. Finally, the research exemption to the DMCA is in effect (for two years, but we can hope it’ll be extended forever).
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EFF has the story of malware from the Kazakhstan government against “journalists and political activists critical of Kazakhstan’s authoritarian government, along with their family members, lawyers, and associates.”
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Announcing Let’s Encrypt, a new free certificate authority. This is a joint project of EFF, Mozilla, Cisco, Akamai, and the University of Michigan.
This is an absolutely fantastic idea.
The anchor for any TLS-protected communication is a public-key certificate which demonstrates that the server you’re actually talking to is the server you intended to talk to. For many server operators, getting even a basic server certificate is just too much of a hassle. The application process can be confusing. It usually costs money. It’s tricky to install correctly. It’s a pain to update.
Let’s Encrypt is a new free certificate authority, built on a foundation of cooperation and openness, that lets everyone be up and running with basic server certificates for their domains through a simple one-click process.
The key principles behind Let’s Encrypt are:
- Free: Anyone who owns a domain can get a certificate validated for that domain at zero cost.
- Automatic: The entire enrollment process for certificates occurs painlessly during the server’s native installation or configuration process, while renewal occurs automatically in the background.
- Secure: Let’s Encrypt will serve as a platform for implementing modern security techniques and best practices.
- Transparent: All records of certificate issuance and revocation will be available to anyone who wishes to inspect them.
- Open: The automated issuance and renewal protocol will be an open standard and as much of the software as possible will be open source.
- Cooperative: Much like the underlying Internet protocols themselves, Let’s Encrypt is a joint effort to benefit the entire community, beyond the control of any one organization.
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