Jump to content

Exchange Security Fixes - 03/2021


Recommended Posts

Hallo zusammen,

 

das Exchange Team hat nor vor Veröffentlichung der März-CU´s diverse Security-Fixes veröffentlicht, den Artikel wie immer in EN findet ihr hier:

 

https://techcommunity.microsoft.com/t5/exchange-team-blog/released-march-2021-exchange-server-security-updates/ba-p/2175901

 

Es wurden Fixes veröffentlicht für:

Exchange Server 2010 (RU 31 for Service Pack 3 – this is a Defense in Depth update)

Exchange Server 2013 (CU 23)

Exchange Server 2016 (CU 19, CU 18)

Exchange Server 2019 (CU 8, CU 7)

 

Bitte beachten und so bald als möglich installieren!

 

Edited by Nobbyaushb
URL
  • Like 1
  • Thanks 1
Link to post
Zitat

Because we are aware of active exploits of related vulnerabilities in the wild (limited targeted attacks), our recommendation is to install these updates immediately to protect against these attacks.

 

...

 

The last Exchange 2016 and Exchange 2019 CU’s were released in December of 2020. Are new CU’s releasing in March 2021?

We are still on schedule to release Exchange Server 2016 CU 20 and Exchange Server 2019 CU 9 in March 2021 and those CUs will contain the Security Updates mentioned here (along with other fixes). Our strong recommendation is to install security updates immediately.

Released: March 2021 Exchange Server Security Updates - Microsoft Tech Community

 

Zitat

Technical details

 

Microsoft is providing the following details to help our customers understand the techniques used by HAFNIUM to exploit these vulnerabilities and enable more effective defense against any future attacks against unpatched systems.

 

CVE-2021-26855 is a server-side request forgery (SSRF) vulnerability in Exchange which allowed the attacker to send arbitrary HTTP requests and authenticate as the Exchange server.

 

CVE-2021-26857 is an insecure deserialization vulnerability in the Unified Messaging service. Insecure deserialization is where untrusted user-controllable data is deserialized by a program. Exploiting this vulnerability gave HAFNIUM the ability to run code as SYSTEM on the Exchange server. This requires administrator permission or another vulnerability to exploit.

 

CVE-2021-26858 is a post-authentication arbitrary file write vulnerability in Exchange. If HAFNIUM could authenticate with the Exchange server then they could use this vulnerability to write a file to any path on the server. They could authenticate by exploiting the CVE-2021-26855 SSRF vulnerability or by compromising a legitimate admin’s credentials.

 

CVE-2021-27065 is a post-authentication arbitrary file write vulnerability in Exchange. If HAFNIUM could authenticate with the Exchange server then they could use this vulnerability to write a file to any path on the server. They could authenticate by exploiting the CVE-2021-26855 SSRF vulnerability or by compromising a legitimate admin’s credentials.

HAFNIUM targeting Exchange Servers with 0-day exploits - Microsoft Security

 

HTH

Jan

  • Thanks 1
Link to post

Interessant, ich dachte exchange 2019 hätte gar keinen um Service mehr. :/

CVE-2021-26857 is an insecure deserialization vulnerability in the Unified Messaging service.

 

hat wohl jemand den Code nicht aufgeräumt. ;)

Link to post

Gibt es zum CVE-2021-26855 schon Informationen, wie genau (oder zumindest auf welcher Seite) der SSRF ausgeführt wird? Weil "Port 443 blocken" ist keine brauchbare "Mitigation", aber "den Zugriff auf /xy blocken" (und dann geht Feature XY im OWA temporär nicht mehr) wäre eine. Es ist schon klar, dass Microsoft keinen PoC veröffentlicht, wenn erst die Chinesen den Exploit haben, aber etwas mehr Details wären hilfreich.

Link to post

Naja, hat MS da wirklich in den letzten Monaten schon mal Details zu solchen Dingen veröffentlicht? Die ändern zwar ständig ihr MSRC Portal, aber ich würde sagen, leserlicher wurde es bisher dadurch nicht. Und mehr Details finden sich eben auch nicht.

Muss man wohl wieder warten, bis die PoC dann auf Github auftauchen. ;)

Edited by NorbertFe
Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...