The multiple vulnerabilities discovered in the SIMATIC S7-1500 CPU firmware may allow attackers to perform denial-of-service (DoS) attacks with specially crafted HTTP(S), ISO-TSAP, or Profinet network packets.
Read ICS-CERT Security Advisory here – http://ics-cert.us-cert.gov/advisories/ICSA-14-073-01
Read Siemens Security Advisory here – http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-456423.pdf