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Re: Loading Rootkit using SystemLoadAndCallImage
From: Fernando Trias <fernando () pedestalsoftware com>
Date: Tue, 5 Sep 2000 17:11:14 -0400

1. A new release of IPD now traps the ZwSetSystemInformation call and
prevents rootkit.com's latest rootkit. Get the developer's version at
http://www.pedestalsoftware.com/intact/ipd/index.htm

2. I think rootkit.com's code has a bug. On line 19, it says "typedef
unsigned long NTSTATUS" when that should be "typedef long NTSTATUS".
Otherwise, the macro on line 20 will always be true since an unsigned value
is always greater than or equal to 0; this means you will never know when
the rootkit fails to load.

3. Other comments:

When we wrote the Integrity Protection Driver (IPD), we were trying to
develop a framework to try to address the issues that Greg Hoglund and
other rootkit developers bring up.

Perhaps I don't understand why Greg Hoglund thinks anti-rootkit software is
useless, but to argue that protection against existing rootkits is useless
because there's no protection for future unknown rootkits is missing the
point. IPD is analogous to anti-virus software. Anti-virus software only
stops known viruses. Does that mean it is useless because it lets new ones
through? No. It still reduces your overall risk and every company uses
anti-virus software.

We are committed to providing the security community with free and open
tools to combat the serious deficiencies in NT/2000 that make rootkits
possible. Others are committed to pointing out these deficiencies so that,
presumably, they can be addressed and Microsoft will be forced to alter
it's kernel. Long term, altering NT/2000 is the right way to proceed. But
until that day, people still need to protect themselves.

We therefore ask that if anyone discovers a method to bypass IPD to please
let us know before publishing it so that we may provide a patch. This is
similar to the accepted vendor notification norms of BUGTRAQ.

At 12:31 PM 8/29/2000 -0700, Greg Hoglund wrote:
Greets,

For a while there has been a thread on NTBUGTRAQ about kernel-mode
protection from rootkits.  This is good - the whole point of our rootkit.com
project is to get people thinking about the problem.  For example, there is
now an ANTI-Rootkit (called Integrity Protection Driver) from Pedestal
Software.

At the Blackhat Briefings this year, more than a couple smart people talked
about how many ways you can load code into the NT kernel - the obvious
reaction to the whole "anti-rootkit" idea.  Most of the rootkit developers
were in on this - so we decided to change the windows rootkit in response.

Up until now, the windows rootkit has been a driver.  BUT, there is no
reason that a rootkit has to operate as a driver - or a loadable module.

Last year we released rootkit to prove that user-mode 'integrity' software
is completely meaningless.  Think about it - anyone who hacks your system is
going to be able to load a kernel mod - period.  This is 100% guaranteed.
If an attacker gets into your system using a user-level account, they will
then obtain administrator - which has all the power you'll ever need to load
kernel-mode code.  Given this fact, it is easy to see that your 'host' based
solutions are completely vulnerable to modification without your knowledge.

The idea of putting your integrity protection into the kernel is a very good
one - but that isn't going to be done 'right' until Microsoft does it
themselves.  And, _when_ they do, a whole 'security' market vanishes.

One of the ideas presented to load kernel mode code was to use an
undocumented entry point into kernel-space - such as the /dev/physicalmemory
device, or a syscall that uses 'SystemLoadAndCallImage'.  We could continue
to beat this down, but the fact is there is no OS-supported leverage point
to control access into kernel mode - and becuase of this, new entry points
can always be discovered.

Assuming Microsoft actually fixes the NT architecture to protect against
this sort of thing - there is still the idea of finding buffer overflows in
the kernel itself.  Every third party driver you install opens you up to
possible buffer overflows thru IOCTL() commands and even normal read/write
messages.  Even the default drivers in NT may be vulnerable to this.

While the rootkit was being handled as a driver, we used the service control
manager to load or remove the driver from kernel space.  This is standard,
and it requires that the rootkit driver have a registry key in the
CurrentControlSet/Services tree.  This has been changed.  We have changed
the rootkit such that it loads into kernel space with no driver or registry
key required.  We no longer use the service control manager.  Instead,
rootkit now loads into kernel memory using a single interrupt call - an NT
system call known as ZwSetSystemInformation().  Using this call we cause the
rootkit to be immediately loaded into memory and activated.

-Greg Hoglund
http://www.rootkit.com

----------------------------
Fernando Trias                     Pedestal Software, LLC
fernando () pedestalsoftware com    Phone: +1 (508) 520-8960
http://www.pedestalsoftware.com    Fax: +1 (508) 520-8638


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