Siemens SIMATIC STEP 7 (TIA Portal) 12 and 13 before 13 SP1 Upd1 allows man-in-the-middle attackers to obtain sensitive information or modify transmitted data via unspecified vectors.
https://cert-portal.siemens.com/productcert/pdf/ssa-487246.pdf
http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-315836.pdf