Researchers Discover Vulnerabilities in PGP/GPG Email Encryption Plugins, Users Advised to Avoid for Now

[MacRumors]

A warning has been issued by European security researchers about critical vulnerabilities discovered in PGP/GPG and S/MIME email encryption software that could reveal the plaintext of encrypted emails, including encrypted messages sent in the past.

The alert was put out late on Sunday night by professor of computer security Sebastian Schinzel. A joint research paper, due to be published tomorrow at 07:00 a.m. UTC (3:00 a.m. Eastern Time, 12:00 am Pacific) promises to offer a thorough explanation of the vulnerabilities, for which there are currently no reliable fixes.

There are currently no reliable fixes for the vulnerability. If you use PGP/GPG or S/MIME for very sensitive communication, you should disable it in your email client for now. Also read @EFF's blog post on this issue: https://t.co/zJh2YHhE5q #efail 2/4 - Sebastian Schinzel (@seecurity) May 14, 2018

Details remain vague about the so-called "Efail" exploit, but it appears to involve an attack vector on the encryption implementation in the client software as it processes HTML, rather than a vulnerability in the encryption method itself. A blog post published late Sunday night by the Electronic Frontier Foundation said:

"EFF has been in communication with the research team, and can confirm that these vulnerabilities pose an immediate risk to those using these tools for email communication, including the potential exposure of the contents of past messages."

In the meantime, users of PGP/GPG and S/MIME are being advised to immediately disable and/or uninstall tools that automatically decrypt PGP-encrypted email, and seek alternative end-to-end encrypted channels such as Signal to send and receive sensitive content.

Update: The GPGTools/GPGMail team has posted a temporary workaround against the vulnerability, while MacRumors has compiled a separate guide to removing the popular open source plugin for Apple Mail until a fix for the vulnerability is released. Other popular affected clients include Mozilla Thunderbird with Enigmail and Microsoft Outlook with GPG4win. Click the links for EFF's uninstall steps.

Article Link: Researchers Discover Vulnerabilities in PGP/GPG Email Encryption Plugins, Users Advised to Avoid for Now

 

[rodpascoe]

Oh the irony.

 

[flyinmac]

Hmm.... security protocol creates a vulnerability. To protect yourself, stop encrypting your emails???

Interesting.

 

[SteveJUAE]

Hope the alert was not sent by email LOL

 

[341328]

This security stuff is a nightmare.

 

[arekm]

This looks like another clickbait by (almost pseudo) research teams. The problem is within mail software and not PGP encryption standard or tools.

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html

 

[flyinmac]

Hope the alert was not sent by email LOL

Going back to using birds to deliver my messages. Considered pigeons... but I want a bird that can shred anyone who tries to intercept my message. Decided on Hawks.

 

[maflynn]

Hope the alert was not sent by email LOL

I work for a company that had done something similar. Send out an email stating that email was down. Of course we didn't see that notice until they resolved the problem.
[doublepost=1526297277][/doublepost]

This looks like another clickbait by (almost pseudo) research teams. The problem is within mail software and not PGP encryption standard or tools.

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html

From what I've read, it's a bug in PGP, not mail

 

[Detektiv-Pinky]

<snip>
From what I've read, it's a bug in PGP, not mail

I heard differently. It is supposedly a bug affecting any kind of Email encryption using MIME and automatically loading remote content. Also the in-build S/MIME encryption is at risk.

 

[HobeSoundDarryl]

Going back to using birds to deliver my messages. Considered pigeons... but I want a bird that can shred anyone who tries to intercept my message. Decided on Hawks.

Beware the Avian Pox https://tvmdl.tamu.edu/2018/03/27/hawk-diagnosed-with-avian-pox/ , Avian Flu: http://www.cidrap.umn.edu/news-pers...king-big-toll-iowa-virus-found-minnesota-hawk and West Nile: https://www.countynewscenter.com/hawk-tests-positive-for-west-nile-virus-protect-against-mosquitoes/

American Indian smoke signals anyone?

Encrypted by only using them in heavy fog?

 

[simonmet]

I swear half the time these vulnerabilities are by design. It just seems like everything will at some point have a security vulnerability of some form or other.

 

[whooleytoo]

Hmm.... security protocol creates a vulnerability. To protect yourself, stop encrypting your emails???

Interesting.

Exactly my reaction. "Some of your emails may be insecure. So remove this software so that they're all insecure." ??

(Bigger question - why the hell are we still using insecure, spam-tastic email? It's astonishing that no mainstream secure alternative, with disposable addresses has really gained much traction.)

I remember going through an exhaustive security audit for a client (covering hosting, backup policy, security policies, incident management etc.) as they were sending us personal user information. Once we passed, they emailed it to us....

 

[Unregistered 4U]

I heard differently. It is supposedly a bug affecting any kind of Email encryption using MIME and automatically loading remote content. Also the in-build S/MIME encryption is at risk.

Same that I read. Essentially, if you already have the viewing of remote images turned off (which I did awhile ago), then this doesn't work when you read the email. You'd have to read the email THEN click "load images".

 

[belvdr]

From what I've read, it's a bug in PGP, not mail

It's a problem in the mail user agent (MUA), not PGP/GPG. From the mailing list:

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html

The topic of that paper is that HTML is used as a back channel to create an oracle for modified encrypted mails. It is long known that HTML mails and in particular external links like <img href="tla.org/TAG"/> are evil if the MUA actually honors them (which many meanwhile seem to do again; see all these newsletters). Due to broken MIME parsers a bunch of MUAs seem to concatenate decrypted HTML mime parts which makes it easy to plant such HTML snippets.

There are two ways to mitigate this attack

- Don't use HTML mails. Or if you really need to read them use a
proper MIME parser and disallow any access to external links.

- Use authenticated encryption.

It also appears that some versions of OpenPGP already use authenticated encryption. From what I'm reading, this is a really old bug that many wanted to get fixed, but the MUAs fail to fix it.

 

[H3LL5P4WN]

This looks like another clickbait by (almost pseudo) research teams. The problem is within mail software and not PGP encryption standard or tools.

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html

Yeah, cause the EFF would totally benefit from telling people who's lives may depend on encryption to stop using encryption.

 

[apolloa]

The story is confusing on here...

So is it Mac Mail that’s at fault? Or a plug-in you have to have installed yourself?

 

[allpar]

So basically, if I send emails without html, all is OK for the moment?

(Sure looks that way! -> “"Efail": as a temporary workaround against "efail" (https://efail.de ), disable "Load remote content in messages" in Mail → Preferences → Viewing. GPG Suite 2018.2 which mitigates against this attack is coming very soon.”)

 

[KidPub]

@ProtonMail is claiming that the Enigmail plugin for Thunderbird has been patched for this for months...presumably ProtonMail's client is fine, too. I agree with @BrianKrebs that this is really irresponsible by @eff (am EFF member).

 

[vegetassj4]

So, files encrypted outside of mail plugins are still safe?

 

[manu chao]

(Bigger question - why the hell are we still using insecure, spam-tastic email? It's astonishing that no mainstream secure alternative, with disposable addresses has really gained much traction.)

I remember going through an exhaustive security audit for a client (covering hosting, backup policy, security policies, incident management etc.) as they were sending us personal user information. Once we passed, they emailed it to us....

Modern encryption requires that your public key is send to the person wanting to send you an encrypted message. That is usually achieved via a central server. Even PGP uses a central key server (though one is not required to use it). The next task for any messaging service is assign 'addresses'. With email that is done via domain names (of your email provider) but whether your message is really delivered to the right person depends on the domain holder to correctly distribute things to their subdomains (aka email addresses). With Signal, the addressing is done via a phone number (which relies on the phone companies to deliver to the correct device).

Both aspects, delivering the correct public key and sending the message to the correct user rely on trust in the central servers holding the keys and distributing the messages. In an open system (like email where addresses are created by acquiring a domain name, which anybody can do, and distributing subdomains or mobile phone numbers where a huge number of carriers exist with many more mobile virtual network operators on top), you are only as secure as you can trust every individual actor.

With iMessage you trust Apple that you public key is delivered without tampering to the sender of a message to you. Ditto with Whatsapp and Facebook. Signal, Telegram, Line, WeChat all have central servers for that. With open systems like email, you rely on every email provider to not be tampering.

 

[Ted13]

My view - use iMessage, FaceTime or Signal for reliable encrypted communication. If you want to send a long letter, type it up in Pages or Word or ... and then attach it to an iMessage. It will be end to end encrypted for you.

Think of email as sending a postcard - cute but zero privacy.

 

[Janichsan]

This looks like another clickbait by (almost pseudo) research teams.

The guy is professor at one of the local universities here in Münster, so no "pseudo research team". The wording is still alarmistic and the tip to disable encryption as alternative to unsafe encryption is still somewhat idiotic.

So is it Mac Mail that’s at fault? Or a plug-in you have to have installed yourself?

PGP/GPG is a plug-in, but S/MIME is a built-in encryption mechanism. And yes, apparently even the vulnerability of PGP/GPG is Mail's fault.

 

[Dave-Z]

use iMessage, FaceTime or Signal for reliable encrypted communication. If you want to send a long letter, type it up in Pages or Word or ... and then attach it to an iMessage. It will be end to end encrypted for you.

Use of S/MIME or GPG effectively makes email end-to-end encrypted, just like the methods you mentioned. From a technical perspective, these work very similiarly.

Yes, perhaps there's a vulnerability in this implementation, but once it's fixed continuing to use these methods is really quite secure.

 

[lkrupp]

I work for a company that had done something similar. Send out an email stating that email was down. Of course we didn't see that notice until they resolved the problem.
[doublepost=1526297277][/doublepost]
From what I've read, it's a bug in PGP, not mail

From what I’ve read it’s both. A bug in PGP and a flaw in how Mail handles HTML rendering that allows the PGP bug to do its dirty work. And Mail is not the only email client affected, and macOS is not the only platform either. And this sounds like something useful only to state operators targeting specific individuals or corporations. For those paranoids who encrypt their emails to grandma just because, well, that’s a different kind of problem.

 

[Sasparilla]

The workaround is to uncheck "Load Remote Content In Messages" from the Viewing preferences in Mail.

If you care at all about security this shouldn't be checked in the first place (cause you don't want to be auto-loading all HTML email's and their potential security holes, you should just be auto-loading things as plain text from a security perspective).

Fix is coming soon according to the GPGtools folks, perhaps folks are over-reacting?