Multiple nation-state groups are hacking Microsoft Exchange servers

I use Exchange, but the Office 365 variety so rely on Microsoft to patch their own servers. If you run your own, have you patched? It is also worthwhile to check for indicators of compromise (IOCs) using this handy guide…:

Multiple government-backed hacking groups are exploiting a recently-patched vulnerability in Microsoft Exchange email servers.

The exploitation attempts were first spotted by UK cyber-security firm Volexity on Friday and confirmed today to ZDNet by a source in the DOD.

Volexity did not share the names of the hacking groups exploiting this Exchange vulnerability. Volexity did not return a request for comment for additional details.

The DOD source described the hacking groups as “all the big players,” also declining to name groups or countries.


These state-sponsored hacking groups are exploiting a vulnerability in Microsoft Exchange email servers that Microsoft patched last month, in the February 2020 Patch Tuesday.

The vulnerability is tracked under the identifier of CVE-2020-0688. Below is a summary of the vulnerability’s technical details:

  • During installation, Microsoft Exchange servers fail to create a unique cryptographic key for the Exchange control panel.
  • This means that all Microsoft Exchange email servers released during the past 10+ years use identical cryptographic keys (validationKey and decryptionKey) for their control panel’s backend.
  • Attackers can send malformed requests to the Exchange control panel containing malicious serialized data.
  • Since hackers know the control panel’s encryption keys, they can ensure the serialized data is unserialized, which results in malicious code running on the Exchange server’s backend.
  • The malicious code runs with SYSTEM privileges, giving attackers full control of the server.

Microsoft released patches for this bug on February 11, when it also warned sysadmins to install the fixes as soon as possible, anticipating future attacks.


Original article here