Authorization Drift in Evolving Long-Lived Agents (Privilege Grant Continuity Gap)

Technical Analysis

The paper identifies a real conceptual gap: as agents mutate (via memory retention, tool acquisition, delegation, or workflow changes), the authority a user originally granted may no longer correspond to the agent's current capabilities or context, creating a path for authorization scope to silently expand ('authorization drift'). The proposed 'state-bound model' fixes an immutable effect ceiling and a transition envelope at grant time, using complete mediation, sound effect abstraction, attenuating delegation, and monitor integrity to prove that mutation cannot amplify protected effects beyond the original ceiling. This is a governance/access-control framework rather than an attack technique; it does not describe an exploited system, malicious tool, or working payload, but it does map six mutation classes that real-world agent architectures should treat as re-authorization triggers. The relevance to threat analysis is that unconstrained agent evolution (self-modifying prompts, tool acquisition, sub-agent delegation) is exactly the mechanism attackers could otherwise abuse for privilege escalation absent such controls.

Detection Signatures

• N/A - theoretical paper, no indicators of compromise.
• For defenders building agent systems: monitor for agents whose tool/capability set or delegation graph changes without a corresponding re-authorization event.
• Log and alert on privilege or effect-scope increases following agent 'skill acquisition' or memory updates that were not accompanied by explicit user re-grant.

Remediation Steps

1. 1

   Adopt grant-time effect ceilings

   Define an immutable maximum permitted effect scope at the time authorization is issued, independent of later agent capability changes.

2. 2

   Re-authorize on capability mutation

   Require explicit human or policy-engine re-approval when an agent acquires new tools, delegates tasks, or otherwise changes its effective capability set.

3. 3

   Enforce complete mediation

   Route all agent actions through a policy enforcement point that checks current authority against the fixed ceiling rather than trusting agent self-reports.

4. 4

   Distinguish requested vs realized effects

   Validate actual side effects of tool calls against declared intent to detect authority creep from agent-produced evidence.

5. 5

   Attenuate delegation

   Ensure delegated sub-agents can only receive a subset of the delegator's authority, never an expansion of it.