Which of the following would an IS auditor recommend as the MOST effective preventive control...

 Digital watermarks are hidden marks or codes that can be embedded into digital files, such as images, videos, audio, or documents. They can be used to identify the source, owner, or authorized user of the data, as well as to track any unauthorized copying or distribution of the data. Digital watermarks can help prevent data leakage by deterring potential leakers from sharing sensitive data or by providing evidence of data leakage if it occurs.

The other options are not as effective as digital watermarks in preventing data leakage. Ensuring that paper documents are disposed securely can reduce the risk of physical data leakage, but it does not address the digital data leakage that is more prevalent in today’s environment. Implementing an intrusion detection system (IDS) can help detect and respond to cyberattacks that may cause data leakage, but it does not prevent data leakage from insiders or authorized users who have legitimate access to the data. Verifying that application logs capture any changes made can help audit and investigate data leakage incidents, but it does not prevent them from happening in the first place.

References:

What is Data Leakage?

What is Digital Watermarking?