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Sep 23, 2021
SolarMarker Malware Activity
THE THREAT eSentire has observed a recent and significant increase in SolarMarker infections delivered through drive-by download attacks. These attacks rely on social engineering techniques to persuade users to execute malware disguised as document templates. SolarMarker is a modular information-stealing malware; infections may result in the theft of sensitive data including user credentials.…
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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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Aug 25, 2021
eSentire named a Leader in IDC MarketScape for U.S. Managed Detection and Response Services
August 26, 2021 – Waterloo, ON -  eSentire, recognized globally as the Authority in Managed Detection and Response (MDR), announced today that it has been named a Leader in the IDC MarketScape: U.S. Managed Detection and Response Services 2021 Vendor Assessment (doc #US48129921, August 2021). IDC defines the core services an MDR must provide as follows: reduced time for onboarding, 24/7…
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Security advisories — Aug 18, 2021

PoC Released, Active Exploitation of Exchange Vulnerabilities Observed


Active exploitation of previously disclosed Microsoft Exchange vulnerabilities has been observed against researcher honeypots in the wild. Affected versions include Microsoft Exchange Server’s 2013, 2016, and 2019. Patches have been available since May [1].

A known vulnerability in Microsoft Exchange allows attackers to commit arbitrary file upload and execution [1]. In combination with previously reported authentication and privilege escalation vulnerabilities (patched in April) [2], this cluster of bugs is known as ProxyShell. This attack was first demonstrated on August 5, 2021, in a BlackHat presentation [3], followed by scanning for vulnerable devices. Within a week of the disclosure, researchers reported active exploitation against their honeypots [4]. Microsoft has made patches available for all three vulnerabilities [1][2].

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Impacted Products:

The attack chain starts with CVE-2021-31207, an authentication bypass vulnerability. From there, a threat actor can elevate privileges with CVE-2021-34523. Finally, with a foothold in the system and escalated privileges, remote code execution can be achieved with CVE-2021-34473. The publicly released PoC relies on abuse of Autodiscover, mapi, and PowerShell in the victim’s environment [5].


[1] https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-may-11-2021-kb5003435-028bd051-b2f1-4310-8f35-c41c9ce5a2f1
[2] https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-april-13-2021-kb5001779-8e08f3b3-fc7b-466c-bbb7-5d5aa16ef064
[3] https://www.blackhat.com/us-21/briefings/schedule/#proxylogon-is-just-the-tip-of-the-iceberg-a-new-attack-surface-on-microsoft-exchange-server-23442
[4] https://www.bleepingcomputer.com/news/microsoft/microsoft-exchange-servers-are-getting-hacked-via-proxyshell-exploits/
[5] https://github.com/ktecv2000/ProxyShell/blob/main/exploit.py