Data Protection and Security Issues with Network Error Logging

Network Error Logging helps web server operators detect operational problems in real-time to provide fast and reliable services. This paper analyses Network Error Logging from two angles. Firstly, this paper overviews Network Error Logging from the data protection view. The ePrivacy Directive requires consent for nonessential access to the end devices. Nevertheless, the Network Error Logging design does not allow limiting the tracking to consenting users. Other issues lay in GDPR requirements for transparency and the obligations in the contract between controllers and processors of personal data. Secondly, this paper explains Network Error Logging exploitations to deploy long-time trackers to the victim devices. Even though users should be able to disable Network Error Logging, it is not clear how to do so. Web server operators can mitigate the attack by configuring servers to preventively remove policies that adversaries might have added.