Virtual Machine Introspection (VMI) is used by sandbox-based dynamic malware detection and analysis frameworks to observe malware samples while staying isolated and stealthy. Sandbox detection and evasion techniques based on hypervisor introspection are becoming less of an issue since running server and workstation environments on hypervisors is becoming standard and high-end sandboxes manipulate virtual clocks to mask VM execution pauses caused by VMI. However, the fake network environment around a sandbox VM offers opportunities similar to hypervisor introspection for malware to evade. Malware can evaluate the discrepancy between observed performances and a real, presumed network environment of infected targets. VMI pauses also cause visible network performance glitches. To solve this issue we propose to extend virtual clock manipulation to synchronize hardware-accelerated virtual machines with a discrete-event network simulator. The experimental evaluation shows that our proposal can counter attempts to infer VMI activity from network timing observations.