
NtGlobalFlag
Created the Monday 18 March 2019. Updated 3 months, 1 week ago.
The information that the system uses to determine how to create heap structures is stored at an undocumented location in the PEB at offset 0x68
. If the value at this location is 0x70
, we know that we are running in a debugger.
The NtGlobalFlag
field of the Process Environment Block (0x68 offset on 32-Bit and 0xBC on 64-bit Windows) is 0 by default. Attaching a debugger doesn’t change the value of NtGlobalFlag. However, if the process was created by a debugger, the following flags will be set:
FLG_HEAP_ENABLE_TAIL_CHECK
(0x10)FLG_HEAP_ENABLE_FREE_CHECK
(0x20)FLG_HEAP_VALIDATE_PARAMETERS
(0x40)
The presence of a debugger can be detected by checking a combination of those flags.
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