Using HyperDbg

events (show and modify active/disabled events)

Description of 'event' command in HyperDbg.




events [e|d|c] [event number (hex value) | all]


Shows a list of active/disabled events and commands or disables or clears the event(s).


[e|d|c] (optional)

Type of action can be one of the e, d, or c.

e : enables the target event

d : disables the target event

c : clears and removes the target event

[event number (hex value) | all] (optional)

Specifies the target event (you can see the list of events and their unique event numbers by running the 'events' command), you can specify all to apply your action to all active/disabled events.

If you don't specify any parameters to the 'events' command, it shows a list of events and their unique event numbers.


The following command shows the list of active/disabled events.

HyperDbg> events
0 (enabled) !syscall 80
1 (disabled) !sysret 80
2 (enabled) !msrwrite 80 code {90}
3 (enabled) !cpuid

The following command disables an event with event number 1 and then we see the list of all events.

HyperDbg> event d 1
HyperDbg> events
0 (enabled) !syscall 80
1 (disabled) !sysret 80
2 (enabled) !msrwrite 80 code {90}
3 (enabled) !cpuid

The following command enables all of the events and commands.

HyperDbg> event e all
HyperDbg> events
0 (enabled) !syscall 80
1 (enabled) !sysret 80
2 (enabled) !msrwrite 80 code {90}
3 (enabled) !cpuid

The following command clears an event with event number 1.

HyperDbg> event c 1
HyperDbg> events
0 (enabled) !syscall 80
2 (enabled) !msrwrite 80 code {90}
3 (enabled) !cpuid

The following command clears and turns off every enabled and disabled event and commands.

0: kHyperDbg> event c 1


This function works by calling DeviceIoControl with IOCTL = IOCTL_DEBUGGER_MODIFY_EVENTS, you have to send it in the following structure.

typedef struct _DEBUGGER_MODIFY_EVENTS {
UINT64 Tag; // Tag of the target event that we want to modify
UINT64 KernelStatus; // Kerenl put the status in this field
TypeOfAction; // Determines what's the action (enable | disable | clear)

Where Tag is the tag of the event that you want to modify, you should leave KernelStatus as it will be filled by the kernel and shows whether the request was successful or not.

Keep in mind, Tag is not the same as event number, tags start from DebuggerEventTagStartSeed (by default 0x1000000); thus, you can add this value to form a Tag from event number.

TypeOfAction shows what type of action you want the kernel to perform (enable, disable, or clear). It can be one of the following values.


If you want to apply the action to all the events/commands, then you should fill the Tag with the following constant.

#define DEBUGGER_MODIFY_EVENTS_APPLY_TO_ALL_TAG 0xffffffffffffffff

When the request is finished, the kernel fills the user-mode buffer with one of the following values, which indicates whether the request was successful or there was an error.

In the case of success :


In the case of error :



Important note

If you are operating in Debugger Mode, you can enable or disable events while the debuggee is in a halt state. However, if you want to clear an event or all events then you lose the context as the debuggee is continued for some time to process the clear operation.