What We Do
How we do it
Resources
Company
ABOUT ESENTIRE
About Us
eSentire is The Authority in Managed Detection and Response Services, protecting the critical data and applications of 2000+ organizations in 80+ countries from known and unknown cyber threats. Founded in 2001, the company’s mission is to hunt, investigate and stop cyber threats before they become business disrupting events.
Read about how we got here
Leadership Work at eSentire
LATEST PRESS RELEASE
Mar 20, 2023
Exertis and eSentire Partner to Deliver 24/7 Multi-Signal MDR, Digital Forensics & IR Services and Exposure Management to Organisations Across the UK, Ireland, and Europe
Basingstoke, UK– 20 March, 2023. Leading technology distributor, Exertis, announced today that it has bolstered its cybersecurity services, adding eSentire, the Authority in Managed Detection and Response (MDR), to its Enterprise portfolio of offerings. eSentire’s award-winning, 24/7 multi-signal MDR, Digital Forensics & Incident Response (IR), and Exposure Management services will be available…
Read More
Partners
PARTNER PROGRAM
e3 Ecosystem
We provide sophisticated cybersecurity solutions for Managed Security Service Providers (MSSPs), Managed Service Providers (MSPs), and Value-Added Resellers (VARs). Find out why you should partner with eSentire, the Authority in Managed Detection and Response, today.
Learn more
ECOSYSTEM PARTNER RESOURCES
Apply to become an e3 ecosystem partner with eSentire, the Authority in Managed Detection and Response.
Login to the Partner Portal for resources and content for current partners.
Search
Resources
Security advisories — Feb 27, 2019

EFAIL – Vulnerabilities in PGP and S/MIME Encrypted Emails

1 minute read
Speak With A Security Expert Now

Two new vulnerabilities have been discovered impacting multiple email clients. The vulnerabilities impact customers that use OpenPGP or S/MIME to secure email communications. Successful exploitation may allow threat actors to decrypt sensitive email communications when the victim is using a vulnerable email client or plugin. Threat actors combine known weaknesses in the encryption algorithms with automatic rendering of active content to perform this new attack. Threat actors first need to obtain the encrypted messages, then send them to a user with a vulnerable email client.

What we’re doing about it

What you should do about it

Additional information

For a full list of affected email clients, please see the official EFAIL whitepaper1.

There are two techniques for exploiting EFAIL. The first being direct exfiltration which affects both PGP and S/MIME. In this scenario, the adversary intercepts an encrypted email and places it into a new email with HTML tags around the encrypted section. This new email is then sent to the victim. When received by the victim’s mail client, the message is unencrypted, but the additional HTML tags cause a misinterpretation of data, sending the unencrypted message to a remote server where it can be read.

The second technique is the modification of ciphertext using known weaknesses in the Cipher Block Chaining. Since threat actors know the structure of S/MIME emails, they can perform a plaintext attack and embed HTML tags, similar to the first technique.

CVE-2017-176882 and CVE-2017-176893 have been reserved for the PGP and S/MIME vulnerabilities; at this time, the CVE references have not been updated with current information.


References:

[1] Efail: Breaking S/MIME and OpenPGP Email Encryption
https://efail.de/efail-attack-paper.pdf

[2] CVE-2017-17688
https://cve.mitre.org/cgi-bin/cvename.cgi?name=2017-17688

[3] CVE-2017-17689
https://cve.mitre.org/cgi-bin/cvename.cgi?name=2017-17689

View Most Recent Blogs