Ethical Hacking

Learn to find vulnerabilities before the bad guys do! Gain real world hands on hacking experience in our state of the art hacking lab. Course designed and taught by expert instructors with years of penetration testing experience. 12 student maximum in every class. Certification attempt included in every package.
Computer Forensics Training at InfoSec Institute

Gain the in-demand skills of a certified computer examiner, learn to recover trace data left behind by fraud, theft, and cybercrime perpetrators. Discover the source of computer crime and abuse at your organization so that it never happens again. All of our class sizes are guaranteed to be 12 students or less to facilitate one-on-one interaction with one of our expert instructors.




Network Security Incidents
[Top] [All Lists]

Re: Strange SMTP sessions with 'helo=<large negative number>' syntax

Subject: Re: Strange SMTP sessions with 'helo=<large negative number>' syntax
Date: Thu, 29 Dec 2005 10:01:23 +0100
On 28/12/05, max <max@neuropunks.org> wrote:
to=<dylanfans-unsubscribe@dylanirvana.com> proto=SMTP helo=<-1217882552>
Notice that helo section is a negative number (which is why my postfix 
rejects the message)

Spammers sometimes hide IP addresses (in URL) by using a 32 bits
integer. And also that they often use buggy tools.<grin>
Maybe they tried to use this trick in the HELO command?

-1217882552+2^32 = 3077084744 = 183.104.150.72
-1218008120+2^32 = 3076959176 = 183.102.171.200
Both addresses seems to be unassigned, my hypothesis looks wrong :-(

Has anyone noticed this as well?

I don't have this in my logs.

<Prev in Thread] Current Thread [Next in Thread>