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Index > Windows > How to bypass Privileged instruction(0xC0000089) (User mode)

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typedef



Joined: 25 Jul 2010
Posts: 2913
Location: 0x77760000
typedef
I have this snippet in DLL

Read time (second) from CMOS

Code:
mov dx,70h
mov al,0
out dx,al  ;<------------ Happens here
inc dx
in al,dx

    


Is there a good way of doing that?
Post 13 Apr 2011, 03:07
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17279
Location: In your JS exploiting you and your system
revolution
Which version of Windows?

There are many available drivers available for download that allow user mode I/O, but later versions of Windows (Vista and 7) won't load unsigned drivers. Search for Userport (both on this board and the wider Internet), I have used it successfully in the past.
Post 13 Apr 2011, 03:55
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typedef



Joined: 25 Jul 2010
Posts: 2913
Location: 0x77760000
typedef
Ok. Thanks.

I'm using Windows XP, SP 3
Post 13 Apr 2011, 03:59
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typedef



Joined: 25 Jul 2010
Posts: 2913
Location: 0x77760000
typedef
Wait...Hold on..... I'll try it my self in Kernel mode... I have WDK and I was recently making a driver.....
LOL

What am I thinking.....
Post 13 Apr 2011, 04:01
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ouadji



Joined: 24 Dec 2008
Posts: 1081
Location: Belgium
ouadji
proc DriverEntry pDriverObject, usRegistryPath ...
a driver, there is no alternative.
possibly a "callgate", but this raises other problems,
switch to ring0 via a "callgate" isn't completely stable.
Because "far jmp" does not clear interrupt flag.
A driver is the only real solution

_________________
I am not young enough to know everything (Oscar Wilde)- Image
Post 13 Apr 2011, 07:18
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typedef



Joined: 25 Jul 2010
Posts: 2913
Location: 0x77760000
typedef
yup...i just made a driver and it's able to dump 255 bytes from cmos.....interesting....maybe i could find something on the way
Post 13 Apr 2011, 14:19
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sinsi



Joined: 10 Aug 2007
Posts: 693
Location: Adelaide
sinsi
revolution wrote:
Which version of Windows?

There are many available drivers available for download that allow user mode I/O, but later versions of Windows (Vista and 7) won't load unsigned drivers. Search for Userport (both on this board and the wider Internet), I have used it successfully in the past.


There is a boot menu option (a one-time option too) but it's a bit unclear as to unsigned drivers.
Quote:
Disable Driver Signature Enforcement
- Allows drivers containing improper signatures to be installed

Does unsigned=improper?
Post 13 Apr 2011, 14:28
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Alphonso



Joined: 16 Jan 2007
Posts: 294
Alphonso
AFAIK you can self sign and use the test signing option. Since self signed usually has no recognized CA chain then maybe that's what is meant by "improper signatures".
Post 13 Apr 2011, 14:57
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