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Jul 29, 2021
UPDATE: PetitPotam NTLM Relay Attack
THE THREAT PetitPotam is a variant of the NTLM Relay attack discovered by security researcher Gilles Lionel. It is tracked as an authentication bypass vulnerability in Active Directory (Certificate Services); currently no CVE identifier has been assigned to this vulnerability. Proof of Concept (PoC) code released last week [1] relies on the Encrypting File System Remote (EFSRPC) protocol to…
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Jul 12, 2021
Tecala and eSentire Partner to Protect Enterprises across APAC from Business-Disrupting Cyber Attacks
Sydney, 12 July, 2021 - Tecala, Australia’s award-winning technology services and IT consulting provider, today announced it has chosen eSentire, the global Authority in Managed Detection and Response (MDR) cybersecurity services, as their exclusive MDR solution provider in Australia and New Zealand. This partnership will enable Tecala to augment its cybersecurity practice and offer enterprises…
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Security advisories — Feb 27, 2019

Microsoft Exchange Server Elevation of Privilege Vulnerability

2 min read

A new attack technique has been identified by security researcher Dirk-jan Mollema, which could allow an attacker to impersonate other Exchange users and elevate privileges [1].

Microsoft has released updated guidance on this issue which includes security updates to Exchange [2].

Proof-of-concept (PoC) code is available and is simple to use [3]. Customers are advised to test and deploy available security updates as soon as possible.

What we’re doing about it

What you should do about it

Additional information

The attack is conducted by using the Exchange Web Services' PushSubscription service to subscribe for push events, pointing them to the attacker’s machine. Exchange will connect to the attacker’s machine using the PushSubscriptionRequest method where it will attempt to authenticate using NTLM credentials (for the computer account of the Exchange server). These credentials are then relayed to a Domain Controller where the Exchange account can be used to elevate privileges for an account under the attacker’s control.

Unpatched Exchange 2013, 2016 and 2019 have been confirmed as vulnerable to this attack.

References:

[1] https://dirkjanm.io/abusing-exchange-one-api-call-away-from-domain-admin/

[2] https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0686

[3] https://github.com/dirkjanm/PrivExchange

[4] https://blogs.technet.microsoft.com/exchange/2019/02/12/released-february-2019-quarterly-exchange-updates/