According to the the organization's Call for Engagement it is looking for partipants. Here's what the document says:

Fighting Corruption in the Supply Chain

The Anti-Corruption Task Force of the Advisory Group on Supply Chain Sustainability is developing an inspirational "Guide to Fight Corruption in the Supply Chain". The resource will provide concise, practical and operational guidance to smaller and less-experienced companies on establishing anti-corruption procedures and policies within their organization and its suppliers on a multi-tier level. The guide will be short, basic and inspiring. It will showcase specific company examples and contain links to other useful resources on this topic.

Global Compact participants are encouraged to submit examples of how they are integrating anti-corruption measures into their supply chains, including with direct suppliers and sub-suppliers. Learn more about the criteria for examples and how they can be submitted. 

The orginazation is targeting smaller companies that don't have the resources to effectively battle corruption. And the fact is that if a company is of the scale to be able to sustain corrupt practices, then it is likely also able to fend off or strangle any smaller company that it sees as a threat. Their Call for Company Examples is interesting in that it is wide open for reporting of any kind of corruption, and the reporting method is simply a 100-200 word explanation of the corrupt practice emailed to the contact at un.org.

My guess is that the UN is mainly interested in corrupt enterprises that are controlling product traffic and circumventing laws and regulations that fall within the grey zone of international trade. But the way the document and the group charter reads, it is looking to take action against any entity that seems to be interfering with the supply chain in general.