Re: SSH brute force blocking tool

On Fri, 01 Dec 2006, Raphael Marichez wrote:

> You mention (from the attached mail, you've written):

sorry, here's your email

-- 
Raphaël Marichez aka Falco

attached mail follows:

Tavis Ormandy wrote:
> On Tue, Nov 28, 2006 at 04:02:36PM +0000, Tavis Ormandy wrote:
> I notice you also havnt solved the local privilege escalation, this can
> be abused by local users to gain root by attempting to login with the
> username set to a valid passwd entry and then winning the race condition
> by creating a symlink to the system passwd file (of course, there are
> dozens of other attacks).
>
> Thanks, Tavis.

And just what on God's earth does "SOMEONE LOGGING IN WITH USERNAME SET
TO A VALID PASSWORD ENTRY" have to do with this script. Let me take my
script out of the equation for a minute. "SOMEONE LOGS IN WITH A
USERNAME SET TO A VALID PASSWORD ENTRY" don't you think this is a
problem with the system they're on? Please explain to me how because I'm
seriously curious to know how you envision this happening with this
script of mine.

Nov 27 16:31:21 local sshd[67010]: Illegal user dd from 213.134.128.227
awk '($5=="Illegal"||$6=="Illegal")&&$9=="from"{print $10}'

Would stop the insertion attack and only print out the tench field if
fields 5, 6 and 9 match Illegal user from.

So that would pretty much minimize the attack on name insertion. If I
wanted to I could also make sure that if someone came after field 10,
then ignore the entire line:
Nov 27 16:31:21 local sshd[67010]: Illegal user dd from 213.134.128.227

But before you shoot back let me send your response for you:

Tavis Ormandy will write:
> "Someone could log in using: "Illegal User foo from
$OWNIPADDRESS"@host which would make an entry:
> Nov 27 16:31:21 local sshd[67010]: Illegal user dd from Illegal User
foo from $OWNIPADDRESS 213.134.128.227"

SO let me restate. I could modify it to look at lines 5, 6, and 9 ...
Take a look at the tenth column and if anything comes after
that...Ignore that entire line... Should I have done so, maybe... Will I
do so... Maybe...

But wait there's more... Before you respond back Tavis, I will do so for
you:

Tavis Ormandy will write:
> "Someone could cause a race condition in awk that will allow peanut
butter to seep into my colo"

Sorry can't help you there.

As to a fix to someone injecting ranDumb addresses. That same awk
statement above will work but if they're doing some netcat voodoo, then
feel free to shoot off another email on how my script broke TCP/IP entirely.

-- 
====================================================
J. Oquendo
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x1383A743
sil . infiltrated @ net http://www.infiltrated.net 
The happiness of society is the end of government.
John Adams

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/