Siemens SIMATIC S7-300 CPU devices allow remote attackers to cause a denial of service (defect-mode transition) via crafted packets on (1) TCP port 102 or (2) Profibus.
https://www.exploit-db.com/exploits/44802/
https://ics-cert.us-cert.gov/advisories/ICSA-15-064-04
https://cert-portal.siemens.com/productcert/pdf/ssa-987029.pdf
http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-987029.pdf