An apparatus, comprising: a first processing resource to execute a program code, the program code including a monitoring block, the monitoring block, during execution of the program code, to: issue a check request to a validation program, on receipt of an ignore check signal provided by the validation program as a response to the check request, decline to calculate a first security value for a part of the program code. and otherwise, calculate the first security value and send the first security value to the validation program; and a second processing resource separate from the first processing resource, the second processing resource to run the validation program, the validation program to: send an ignore check signal to the monitoring block in response to the check request, or receive the first security value, check the first security value against a second security value calculated from a corresponding part of a reference copy of the program code to obtain a check result, and return the check result to the monitoring block, wherein the monitoring block is to perform a security-related action in response to a check result indicating a mismatch between the first security value and the second security value; and wherein an amount of ignore check signals sent to the monitoring block is determined dependent on a threat environment, set by a management server or determined through the analysis of previous check results. issue a check request to a validation program, on receipt of an ignore check signal provided by the validation program as a response to the check request, decline to calculate a first security value for a part of the program code. and otherwise, calculate the first security value and send the first security value to the validation program; and a second processing resource separate from the first processing resource, the second processing resource to run the validation program, the validation program to: send an ignore check signal to the monitoring block in response to the check request, or receive the first security value, check the first security value against a second security value calculated from a corresponding part of a reference copy of the program code to obtain a check result, and return the check result to the monitoring block, wherein the monitoring block is to perform a security-related action in response to a check result indicating a mismatch between the first security value and the second security value; and wherein an amount of ignore check signals sent to the monitoring block is determined dependent on a threat environment, set by a management server or determined through the analysis of previous check results. send an ignore check signal to the monitoring block in response to the check request, or receive the first security value, check the first security value against a second security value calculated from a corresponding part of a reference copy of the program code to obtain a check result, and return the check result to the monitoring block, wherein the monitoring block is to perform a security-related action in response to a check result indicating a mismatch between the first security value and the second security value; and wherein an amount of ignore check signals sent to the monitoring block is determined dependent on a threat environment, set by a management server or determined through the analysis of previous check results.