Typical severity: Low. An attacker may intercept and log encrypted transmissions for the purpose of analyzing metadata such as packet timing and sizes. Although the actual data may be encrypted, this metadata may reveal valuable information to an attacker. Note that this attack is applicable to VOIP data as well as application data, especially for interactive apps that require precise timing and low-latency (e.g. thin-clients).
Distort packet sizes and timing at VPN layer by adding padding to normalize packet sizes and timing delays to reduce information leakage via timing.