Snail Mail Beats Email Any Day: On Effective Operator Security Notifications in the Internet

TL;DR

This study compares traditional email notifications with mailed letters for alerting website operators about security issues, finding letters significantly improve remediation success, though detailed attack descriptions may reduce response rates.

Contribution

It introduces and evaluates the effectiveness of mailed letters as an alternative to emails for security notifications, highlighting the importance of contact method in remediation success.

Findings

Letters outperform emails in remediation rates by up to 25 percentage points.

Manually collected addresses greatly increase notification delivery success.

Detailed attack descriptions can negatively impact remediation responses.

Abstract

In the era of large-scale internet scanning, misconfigured websites are a frequent cause of data leaks and security incidents. Previous research has investigated sending automated email notifications to operators of insecure or compromised websites, but has often met with limited success due to challenges in address data quality, spam filtering, and operator distrust and disinterest. While several studies have investigated the design and phrasing of notification emails in a bid to increase their effectiveness, the use of other contact channels has remained almost completely unexplored due to the required effort and cost. In this paper, we investigate two methods to increase notification success: the use of letters as an alternative delivery medium, and the description of attack scenarios to incentivize remediation. We evaluate these factors as part of a notification campaign utilizing manually-collected address information from 1359 German website operators and focusing on unintentional information leaks from web servers. We find that manually collected addresses lead to large increases in delivery rates compared to previous work, and letters were markedly more effective than emails, increasing remediation rates by up to 25 percentage points. Counterintuitively, providing detailed descriptions of possible attacks can actually *decrease* remediation rates, highlighting the need for more research into how notifications are perceived by recipients.