If you look back along the evolutionary steps of mainframe security, APF libraries play a leading role – due to their “superpower.” Until the 1980s, “almost anyone” working on a mainframe was able and allowed to define one themselves. In most cases, there was no APF library protection at all. Then there was a phase where APF-related auditing received more and more attention, and correspondingly became an important audit issue.

The attention that “APF” received as a security risk has continued to increase over time. Today, it has almost reached the highest level of awareness: only a very few members of a company’s mainframe team are allowed to define a new APF library or update existing ones. Any such action requires prior permission, not just some documentation after it has happened. On our customer visits, we have seen companies where a new APF library requires not only an official change request, but up to “5 signatures.” Otherwise, you lose your job. Correspondingly, relentless monitoring and compliance reporting has become standard for the “APF” risk, resulting in real-time security alerts by a SIEM if corresponding rules are bypassed.

So far, so good. Now that there is great awareness of “APF,” the question will be if the entire mainframe security mission has now been accomplished? Or what’s the next superpower, following “APF,” that mainframe users need to focus on?

Based on our worldwide penetration testing experience, we have determined that “System REXX” and “BCPii” are two further members of the superpower league; both are good candidates for becoming the next “big focus.” In recent years, both z/OS features have been improved so that they are now “easy-to-use” functions. But there is no free lunch. As a consequence, highly critical operations became minimally complex, and you have to “pay” the price for setting up gap-free security measures. User-friendly and easy-to-use superpower features are an invitation to attackers. Complexity is a kind of protection. Compared to assembler programming or disassembling machine code, REXX programming is pretty trivial!

This is why SF-Sherlock focuses intensively on both of these areas. Please feel free to contact us to discuss additional details of what is necessary to properly protect System REXX and BCPii.