VoidSec (16)

Last Login: September 14, 2020
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Hi @ccondon-r7 I have one clients that were further compromised using this vulnerability (attackers already had a foothold into his network and used this vulnerability to gain Domain Admin and push a ransomware). As I’m not part of the IR team I’m still waiting for them to gather more details on the attack.

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Technical Analysis

Unauthenticated attacker, able to directly connect to a Domain Controller over NRPC will be able to reset the Domain Controller’s account password to an empty string, thus enabling the attackers to further escalate their privileges to Domain Admin.

The exploit will be successful only if the Domain Controller uses the password stored in Active Directory to validate the login attempt, rather than the one stored locally as, when changing a password in this way, it is only changed in the AD. The targeted system itself will still locally store its original password.
Target computer will then not be able to authenticate to the domain anymore, and it can only be re-synchronized through manual action.
In test lab a successful attack broke the following functionalities when targeting a Domain Controller: DNS functionality and/or communication with replication Domain Controllers.

Checker and Exploit code
Original research and white-paper: Secura – Tom Tervoort

6
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Technical Analysis

CVE-2020-1337 is a bypass of (PrintDemon) CVE-2020-1048’s patch via a Junction Directory, made to remediate an Elevation of Privileges (EoP)\Local Privilege Escalation (LPE) vulnerability affecting the Windows’ Print Spooler Service. The vulnerability does require low privilege access and for the spooler service to restart.
The patch appeared in Microsoft’s patch Tuesday (11th August 2020) – https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2020-1337#ID0EWIAC.

Vulnerability description, root cause analysis and PoC code on https://voidsec.com/cve-2020-1337-printdemon-is-dead-long-live-printdemon/