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

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.

GPGMail pane
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.


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.

Top Rated Comments

flyinmac Avatar
72 months ago
Hmm.... security protocol creates a vulnerability. To protect yourself, stop encrypting your emails???

Interesting.
Score: 12 Votes (Like | Disagree)
arekm Avatar
72 months ago
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
Score: 7 Votes (Like | Disagree)
rodpascoe Avatar
72 months ago
Oh the irony.
Score: 6 Votes (Like | Disagree)
flyinmac Avatar
72 months ago
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.
Score: 4 Votes (Like | Disagree)
Detektiv-Pinky Avatar
72 months ago

<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.
Score: 3 Votes (Like | Disagree)
belvdr Avatar
72 months ago
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.
Score: 3 Votes (Like | Disagree)

Popular Stories

apple card 1

Apple Ending Apple Card Partnership With Goldman Sachs

Tuesday November 28, 2023 3:09 pm PST by
Apple is ending its credit card partnership with Goldman Sachs, according to The Wall Street Journal. Apple plans to stop working with Goldman Sachs in the next 12 to 15 months, and it is not yet clear if Apple has established a new partnership for the Apple Card. Apple and Goldman Sachs will dissolve their entire consumer partnership, including the Apple Card and the Apple Savings account....
ios 17 namedrop

Police Departments and News Sites Spreading Misinformation About How iOS 17 NameDrop Feature Works

Monday November 27, 2023 5:11 pm PST by
Apple with iOS 17.1 and watchOS 10.1 introduced a new NameDrop feature that is designed to allow users to place Apple devices near one another to quickly exchange contact information. Sharing contact information is done with explicit user permission, but some news organizations and police departments have been spreading misinformation about how functions. As noted by The Washington Post,...
Apple Logo

Apple Discontinued These 5 Products This Year

Monday November 27, 2023 7:03 am PST by
As the end of 2023 nears, now is a good opportunity to look back at some of the devices and accessories that Apple discontinued throughout the year. Apple products discontinued in 2023 include the iPhone 13 mini, 13-inch MacBook Pro, MagSafe Battery Pack, MagSafe Duo Charger, and leather accessories. Also check out our lists of Apple products discontinued in 2022 and 2021. iPhone Mini ...
iOS 17

iOS 17.1.2 Update for iPhone Likely to Be Released This Week

Monday November 27, 2023 8:24 am PST by
Apple will likely release iOS 17.1.2 this week, based on mounting evidence of the software in our website's analytics logs in recent days. As a minor update, iOS 17.1.2 should be focused on bug fixes, but it's unclear exactly which issues might be addressed. Some users have continued to experience Wi-Fi issues on iOS 17.1.1, so perhaps iOS 17.1.2 will include the same fix for Wi-Fi...
iOS 17

Everything New in iOS 17.2 Beta 4

Tuesday November 28, 2023 12:18 pm PST by
Apple is wrapping up development on iOS 17.2, with the update expected to come out in December. While we're getting to the end of the beta testing period, Apple is still tweaking features and adding new functionality. We've rounded up everything new in the fourth beta of iOS 17.2. Default Notification Sound Under Sounds & Haptics, there's a new "Default Alerts" section that allows you to ...
All New CarPlay Five New Features Article 2

What to Expect From All-New CarPlay, Still Listed as Coming 'Late 2023'

Tuesday November 28, 2023 7:44 am PST by
At WWDC in June 2022, Apple previewed the next generation of CarPlay, promising deeper integration with vehicle functions like A/C and FM radio, support for multiple displays across the dashboard, increased personalization, and more. Apple's website still says the first vehicles with support for the next-generation CarPlay experience will be announced in "late 2023," but it has not shared...
Google Drive

Some Google Drive Users' Files Have Mysteriously Vanished

Tuesday November 28, 2023 3:55 am PST by
Google Drive users have been warned not to disconnect their account within the Google Drive for desktop app, after a spate of reports of files going missing from the cloud service. Alarm bells began ringing last week on Google's community support site when some users reported files mysteriously disappearing from Google Drive, with some posters claiming six or more months of data had...