RE: NSLOOKUP.EXE

["Brett Moore" <brett () softwarecreations co nz>]

Hi all..

On win32 systems, it is a common misconseption that buffer overflows in
local executables through
command line arguments do not present much of a security risk.

However they do give an attacker another avenue of attack. For example.

going back to the long unicode/double decode vulnerabilities where one
simple solutions was
to remove the cmd.exe program. Authough some commands could still be run
through other programs
such as attrib and more, for directory listing and file reading, command
execution is limited.

But with the help of a local exe that is vulnerable to command line
overflow, couldnt an attacker
use something similar to
/scripts/..etc../nslookup?<overflowstring with shellcode>
to obtain command access.


Brett

-----Original Message-----
From: K. K. Mookhey [mailto:cto () nii co in]
Sent: Saturday, March 22, 2003 5:41 PM
To: Patrick Webster; vuln-dev () securityfocus com
Subject: Re: NSLOOKUP.EXE


Hi,

On a related note, we had reported the following local BOs to MS. But since,
neither they nor us could come up with any remote exploits for this, I guess
members on this list could check it out. Some of these do not work on Win2K
SP3, but do work on earlier versions.

First:
C:\>regsvr32 AAAAAAA...(1300 times)

Second:
C:\>winhlp32
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaa
aaaaaaaaaaaaaaaaaaaaa.exe
This one crashes only at a particular value of A's, not if its any more or
if its any less.

Again, unless any of these runs with elevated privileges, or someone feeds
in data remotely to these exes, the buffer overflows do not represent a
security risk.

K. K. Mookhey
CTO,
Network Intelligence India Pvt. Ltd.
Web: www.nii.co.in
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----- Original Message -----
Hi List,

Can you do anything interesting with this?:

C:\>nslookup
Default Server:  dns.server.net
Address:  111.222.333.444

>
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

Gives error: memory can't be "read" - 0x414141 (aka A).