Adversaries may hook into application programming interface (API) functions used by processes to redirect calls for execution and privilege escalation means. Windows processes often leverage these API functions to perform tasks that require reusable system resources. Windows API functions are typically stored in dynamic-link libraries (DLLs) as exported functions. 
One type of hooking seen in ICS involves redirecting calls to these functions via import address table (IAT) hooking. IAT hooking uses modifications to a processs IAT, where pointers to imported API functions are stored. 
Triton's injector, inject.bin, changes the function pointer of the 'get main processor diagnostic data' TriStation command to the address of imain.bin so that it is executed prior to the normal handler. 
Perform audits or scans of systems, permissions, insecure software, insecure configurations, etc. to identify potential weaknesses. Perform periodic integrity checks of the device to validate the correctness of the firmware, software, programs, and configurations. Integrity checks, which typically include cryptographic hashes or digital signatures, should be compared to those obtained at known valid states, especially after events like device reboots, program downloads, or program restarts.
|M0944||Restrict Library Loading||
Restrict the use of untrusted or unknown libraries, such as remote or unknown DLLs.
|ID||Data Source||Data Component||Detects|
|DS0009||Process||OS API Execution||
Monitor for API calls that can be used to install a hook procedure, such as the SetWindowsHookEx and SetWinEventHook functions. Also consider analyzing hook chains (which hold pointers to hook procedures for each type of hook) using tools or by programmatically examining internal kernel structures.
Verify integrity of live processes by comparing code in memory to that of corresponding static binaries, specifically checking for jumps and other instructions that redirect code flow.