HTB Checkpoint Complete Writeup - AD Recycle Bin Abuse, Malicious VSIX Supply Chain, BadSuccessor dMSA PrivEsc & NTDS.dit Extraction from VM Backup
Checkpoint is a HackTheBox Medium Windows machine running Windows Server 2025 as a Domain Controller. The attack chain starts with low-privilege credentials for alex.turner, who has WRITE access on the AD Recycle Bin container and CREATE_CHILD on the Employees OU. Restoring the deleted user mark.davies and enabling AS-REP roasting recovers reused credentials, granting WRITE on the DevDrop SMB share. A malicious VS Code extension dropped to that share is auto-installed by a scheduled task running as ryan.brooks, yielding the user flag. Privilege escalation uses ryan.brooks's CreateChild permission on the dMSA-holder OU to perform the BadSuccessor attack against svc_deploy, extracting its NT hash from the KERB-DMSA-KEY-PACKAGE Kerberos structure. svc_deploy is in BackupAccess, which grants READ on a VMBackups share containing a VHDX disk image. Mounting the image and extracting NTDS.dit with the SYSTEM hive produces the Administrator NT hash, completing a Pass-the-Hash takeover of the domain.