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Oct 18, 2021
Grief Ransomware Gang Claims 41 New Victims, Targeting Manufacturers; Municipalities; & Service Companies in U.K. & Europe
Grief Operators Earned an Estimated 8.5 Million British Pounds in Four Months Key Findings: The Grief Ransomware Gang (a rebrand of the DoppelPaymer Ransomware Group) claims to have infected 41 new victims between May 27, 2021—Oct. 1, 2021 with their ransomware.Over half the companies listed on Grief’s underground leak site are based in the U.K. and Europe. The Grief Ransomware Gang appears to…
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eSentire is The Authority in Managed Detection and Response Services, protecting the critical data and applications of 1000+ organizations in 70+ 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.
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Oct 12, 2021
eSentire Launches MDR with Microsoft Azure Sentinel Extending Response Capabilities Across Entire Microsoft Security Ecosystem
Waterloo, ON – Oct. 12, 2021 -- eSentire, recognized globally as the Authority in Managed Detection and Response (MDR), today announced the expansion of its award-winning MDR services with Microsoft Azure Sentinel, as part of its integration with the complete Microsoft 365 Defender and Azure Defender product suites supporting Microsoft SIEM, endpoint, identity, email and cloud security services.…
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Security advisories — Feb 27, 2019

EFAIL – Vulnerabilities in PGP and S/MIME Encrypted Emails

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.


[1] Efail: Breaking S/MIME and OpenPGP Email Encryption

[2] CVE-2017-17688

[3] CVE-2017-17689