CVE-2018-21092 An issue was discovered on Samsung mobile devices with M(6.x) and N(7.x) software. A crafted AT command may be sent by the DeviceTest application via an NFC tag. The Samsung ID is SVE-2017-10885 (January 2018). cve.mitre.org/cgi-bin/cvenam…
The other two modes supported by this "./xcsigningtool remote -path ... -certificate ... -portalEndpoint developerservices2.apple.com…" and "./xcsigningtool deviceTest -path ..."