The syllabus for CS Executive changes frequently, especially with amendments in company law and taxation. PDFs found on random forums are often years old. Studying from an outdated version can lead to answering questions based on repealed laws, which is a recipe for failure in the exam hall.
Cybercriminals often use popular search terms like "CS Executive Scanner PDF" to bait students into downloading executable files (.exe) or compromised PDFs. These files can install ransomware, keyloggers (which steal your passwords), or malware on your device. The cost of repairing a hacked laptop or compromised bank account far exceeds the cost of a book.
While a free PDF looks like a saving, consider the "opportunity cost."