Platform dependent weakness. This issue only impacts iSeries platforms. On these platforms, in BIG-IP APM versions 14.0.0-220.127.116.11, 13.0.0-18.104.22.168, and 12.1.1 HF2-12.1.4, the secureKeyCapable attribute was not set which causes secure vault to not use the F5 hardware support to store the unit key. Instead the unit key is stored in plaintext on disk as would be the case for Z100 systems. Additionally this causes the unit key to be stored in UCS files taken on these platforms.