This whitepaper gives a detailed analysis discussing vulnerabilities surrounding the use of SCADA and PLC systems in modern correctional facilities.
You can download it from the following link: https://packetstormsecurity.com/files/download/103611/PLC_White_Paper_Newman_Rad_Strauchs_July22_2011_Final.pdf
Source: https://packetstormsecurity.com/files/103611/SCADA-And-PLC-Vulnerabilities-In-Correctional-Facilities.html