mailing list archives
Re: NT WinLogon VM contains plaintext password visible in admin mode
From: mad.nutter () MINDLESS COM (Chris Paget)
Date: Thu, 9 Dec 1999 10:42:45 GMT
The API call used is ReadProcessMemory - according to MSDN:
"Before any data transfer occurs, the system verifies that all data in
the base address and memory of the specified size is accessible for
read access. If this is the case, the function proceeds; otherwise,
the function fails."
In this situation, the function fails. It may well be possible to get
around this (probably producing access violations in the process) some
other way; attaching a debugger (such as MSVC) to the winlogon process
does not work - it is unable to read the first 64k bytes of memory,
but is quite happy to disassemble the code (probably because it uses
the same API call). Also, when you stop debugging, you will terminate
winlogon, and hence kill NT.
As far as allowing the process to be debugged goes, all aministrators
are by default granted SeDebugPrivilege, which allows them to debug
practically anything - including winlogon, afaik.
Alternatively, it may be possible to recover the memory space from
either a Windows 2000 hiberfil.sys, or Windows NT's memory.dmp after a
bluescreen; possible even the actual pagefile. In fact, if the
passwords are stored in plaintext, it should be possible by any number
C++ Developer - NetInvest LTD.
chris.paget () netinvest co uk
On Wed, 08 Dec 1999 17:38:18 -0500, you wrote:
When you say the first 10,000 bytes are not accessable, do you mean that is
valid memory, probobly where the passwords are stored, but the system has
been hard coded to deny access to it using the debug apis? What if you set
the global flag to enable debugging of winlogon? Or did you have to do