The Shadowserver Foundation is currently undertaking a project to search for publicly accessible devices that have the Steam Server service running. The goal of this project is to identify openly accessible systems that have the Steam Server service running and report them back to the network owners.
These devices have the potential to be used in UDP amplification attacks and if at all possible, we would like to see these services made un-available to miscreants that would misuse these resources.
Servers that are configured this way have been incorporated into our reports and are being reported on a daily basis.
Information on UDP-based amplification attacks in general can be found in US-CERT alert TA14-017A at: https://www.us-cert.gov/ncas/alerts/TA14-017A
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