Yes, identified a technique known as Synthetic SID Injection .
For more detailed technical analysis, you can view the original research on the Varonis Blog . Yes, identified a technique known as Synthetic SID Injection
An attacker with high privileges (but perhaps needing to maintain long-term, hidden access) adds a non-existent SID to a resource's ACL. These synthetic entries often appear as "Account Unknown"
These synthetic entries often appear as "Account Unknown" or long strings of numbers in the security tab, which administrators frequently ignore as remnants of deleted accounts rather than active threats. Why This Matters
A low-level account created later can suddenly "wake up" with Administrative or Domain Admin rights if those rights were pre-injected into the synthetic SID.
Once a new user or group is created and assigned that specific SID, they automatically inherit all the "synthetic" permissions previously injected, often without appearing in standard audit logs as a new permission grant. Why This Matters