Citrix Systems, Inc.
Blocking Routine Redirection

Abstract:

Disclosed herein are methods, systems, and computer-readable media for blocking attempts at runtime redirection and attempts to change memory permissions during runtime. The present disclosure describes features that enable runtime detection of an attempt to redirect routines or change memory permissions, and determining whether to allow or deny the attempt. Such features may include changing memory write permissions on memory segments, such as those segments used by dynamic loaders after call associations have been saved or otherwise created. Other features may include swapping the addresses of system routines (e.g., open, read, write, close, etc.) to new routines that perform the same function as well as additional functionality configured to detect attempts to redirect or change memory permissions. Once detected by the new routine during runtime, a determination may be made to deny or allow the call based on a policy.