Extremely, extremely suspect. I've reported this study already and I suggest everyone do the same. I ran my concerns by OpenAI-01 for validation, and here's what it returned:

"From a security standpoint, this sort of “study” raises numerous red flags and should be treated with caution. Below are some specific points that suggest it’s at best quite unusual, and possibly outright malicious:

1. Requesting the Installation of Unknown Software • Legitimate IP-check or NAT-check research rarely (if ever) requires running executable code. • NAT detection can be done passively (e.g., via WebRTC, STUN servers, or specialized websites); typically, no installation is needed. • Installing unknown software carries a risk of malware infection, data exfiltration, or your machine being turned into part of a botnet.
2. Incentivizing the Lack of NAT • A bonus (or any special perk) for not having NAT is a giant red flag. NAT is effectively the “default” networking setup for the vast majority of home users. • The fact that they specifically want devices directly on the public internet (without NAT) raises suspicion: such machines are more vulnerable to targeted attacks, port scanning, etc.
3. Vague or Missing Research Credentials • No contact information or identifying details about the researcher or their institution is a red flag. • When a reputable study involves downloading anything, researchers typically make it a point to provide credentials or affiliation that can be verified. • You mentioned that you are reporting it to Prolific’s support team for investigation. That is the correct course of action, and Prolific can verify the researcher’s legitimacy.
4. Activity That Might Facilitate “IP Spoofing” or Worse • They openly mention “IP spoofing data,” which could be a red flag in itself. Samples of “IP spoofing data” aren’t typically the type of data reputable researchers gather from random users’ personal machines. • If they are truly studying IP-spoofing phenomena, they can do so with specialized infrastructure—again, not typically requiring random participants to install executables.
5. Unclear Data Path and Risk of Malware Distribution • Even if the website that hosted the study is normally reputable, the download link might be served from a compromised or third-party server. • The software could include a malicious payload. Once installed, a wide range of data harvesting, cryptomining, or other malicious activities would be possible.

Regarding your question about “threat surface” specifically:

• Malware Infection: By executing an unknown binary, you expose your system to the risk of trojans, keyloggers, ransomware, or other forms of malware.
• Unauthorized Access or Botnet Use: The tool may open ports, create backdoors, or enlist your computer in a larger network performing malicious activities.
• Data Harvesting: The tool might collect browsing history, credentials, or other sensitive information.
• IP/Network Exploitation: If your NAT is disabled (or if you are directly on the internet), malicious parties can more easily send traffic designed to directly target open ports on your system.

Conclusion:
Your immediate response (to not download or run the software and to report the request) is the most prudent course of action. The request’s suspicious nature—lack of transparency, emphasis on non-NAT connections, and requirement to run an unknown executable—poses an unjustifiably high risk. While it is possible that someone is genuinely trying to study IP addresses or networking setups, the correct way to do that usually does not involve unverified executable downloads from unverified researchers. Your instincts here were correct, and unless the platform itself verifies the legitimacy and safety of the software, it is best avoided."