Simple Certificate Enrollment Protocol (SCEP) does not strongly authenticate certificate requests made by users or devices. (Link updated 12/14/2018)
IETF Internet-Draft draft-nourse-scep-23 "...defines a protocol, Simple Certificate Enrollment Protocol (SCEP), for certificate management and certificate and CRL queries in a closed environment." Mobile Device Management (MDM) is defined as "...software that secures, monitors, manages and supports mobile devices deployed across mobile operators, service providers and enterprises. MDM functionality typically includes over-the-air distribution of applications, data and configuration settings for all types of mobile devices, including mobile phones, smartphones, tablet computers, ruggedized mobile computers, mobile printers, mobile POS devices, etc." Multiple MDM software packages use SCEP as a method to handle certificate management and certificate CRL queries within an organization.
When a user or a device requests a certificate, the SCEP implementation may require a challenge password. It may be possible for a user or device to take their legitimately acquired SCEP challenge password and use it to obtain a certificate that represents a different user with a higher level of access such as a network administrator, or to obtain a different type of certificate than what was intended. It is also possible for SCEP implementations or system administrators to not require the challenge password, or to share a static password across many users.
Additional information can be found in Certified Security Solutions, Inc's The Use of the Simple Certificate Enrollment Protocol (SCEP) and Untrusted Devices whitepaper.
An attacker could elevate their permissions by requesting a certificate of a different, possibly higher privileged user that would allow them to access resources that they would not otherwise be able to access.
We are currently unaware of a practical solution to this problem.
Thanks to Ted Shorter of Certified Security Solutions for reporting this vulnerability.
This document was written by Michael Orlando and Art Manion.
|Date First Published:||2012-06-27|
|Date Last Updated:||2018-12-14 17:19 UTC|