Microsoft Internet Explorer Enhanced Protected Mode Read-Restrictions Bypass Vulnerability

2015-07-14T00:00:00
ID ZDI-15-331
Type zdi
Reporter Ashutosh Mehra (https://twitter.com/ashutoshmehra)
Modified 2015-11-09T00:00:00

Description

This vulnerability allows remote attackers to partially escape AppContainer limitations on vulnerable installations of Microsoft Internet Explorer. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the IE broker process when processing a file name for reading in the routine IShdocvwBroker::MOTWCreateFileW. Using a directory junction and a symbolic link, code running inside the EPM AppContainer can read any file that the normal user account can read, bypassing the restrictions designed into EPM.