AbstractTo exploit the human as the "back door" to compromising well-protected information systems of organizations, phishing-type attacks are becoming increasingly sophisticated. There is however a significant lack of real-world studies of phishing campaigns in industrial settings even though it is a wide-spread way to hack information systems of organizations and many notorious cyberattacks started with some sort of a human exploitation. To fill this void, we conducted a case study in a large Central European manufacturing company Manco (fake company name) and observed the targeted employees' and IT department staff's response to a phishing campaign. Even though the IT department staff reacted very fast (their procedures started fifteen minutes after the first phishing e-mail was sent), results suggest significant data leakage and a high potential for successful malware installation. The observed click rate was 69.4 percent and real personal data submission rate was at least 49.0 percent. The average response time of targets (i.e., time between sending the phishing e-mail and visiting the phishing website) was 20 minutes, from 25 seconds to 203 minutes. The results suggest that a phishing campaign can be successful even if the targeted organization's response time is very short. Also, the phishing campaign may not be effective only due to the susceptibility of targets but also due to the investigative techniques of the first responders.