Mobile Device Certificate Enrollment: Are You Vulnerable?

July 3rd, 2012

Last week, US-CERT published a vulnerability note on the Simple Certificate Enrollment Protocol (SCEP). The vulnerability was reported by Certified Security Solutions, a consulting company with extensive Windows and PKI deployment experience. The company’s summary of the vulnerability is here. This vulnerability—when combined with two additional pieces of information—enables an attacker to impersonate another user when enrolling for an X.509 certificate.

For short-term mitigation of the SCEP vulnerability, organizations should use unique shared secrets for each enrollment request. Frequently many organizations use the same shared secret for all of the devices, or worse fail to use the shared secret at all. Additionally, organizations should leverage an LDAP proxy service and/or a directory synchronization service in an effort to limit exposure of the directory, which would enable attackers to query for user distinguished names.

Moving forward, organizations need to perform better user proofing prior to certificate issuance. The best approach may be the use of MDM solutions from vendors including AirWatch, Good Technology, Fiberlink, MobileIron, and Zenprise[4]. These products replace (or proxy) the SCEP enrollment process to prevent the switch of the distinguished name. Certified Security Solutions provides an alternative solution to via its SCEP Validation Service (read about how it works here, on page 7) that enforces the coupling of distinguished name to SCEP secret via a certificate authority plugin.

By Mark Diodati, Gartner

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