Solved

Possibility of a whitelisted (Internet) IP address being spoofed

Posted on 2016-07-29
4
108 Views
Last Modified: 2016-08-01
Currently we don't permit Tcp25 from public Internet to our Exchange server:
all emails go to our internet-facing ProofPoint , then only ProofPoint forward
it our Exchange 2010 server

We plan to permit Tcp 25 direct into our local Exchange 2010 server from an
IP address ie whitelist this public IP address which is our HQ's ProofPoint IP:

a) if it's only a firewall rule that permit our HQ's ProofPoint IP to come in to
    our Exchange server, I guess this IP can be spoofed.  What if this IP is also
    whitelisted, can it be spoofed as well?  I read only Udp can be spoofed or
    is this mistaken?

b) is there any risk of MITM attack for this forwarding ?  The forwarded emails
     are not encrypted
0
Comment
Question by:sunhux
  • 2
4 Comments
 
LVL 17

Accepted Solution

by:
Malmensa earned 250 total points
ID: 41734298
A) Probably not. A device spoofing your IP address would somehow need to be able to the routed from and too.

B) In theory, anyone who can get to see your traffic could implement a "Man in the middle" attack, unless encryption is used. Unencrypted email is not very secure.
0
 
LVL 93

Assisted Solution

by:John Hurst
John Hurst earned 250 total points
ID: 41734560
We plan to permit TCP 25 direct

At a client, my own consulting machine has a DHCP reservation and then that IP address is allowed in the Juniper firewall so that I may send out email separately from their email system.

I do not think you are at excessive risk for doing this. My machine does not compromise the client network.
0
 

Author Comment

by:sunhux
ID: 41734739
https://community.mimecast.com/docs/DOC-1419

Refer to above link: there are indications in the link that allude to IP addr spoofing:

Create an Anti-Spoofing Policy to Allow "Spoofing Based on IP"

5.Enter the list of hostnames to apply the bypass to in the Hostnames box. Confirmation is issued
   that the "IP address used by the sending server matches the hostname specified"
   ie for the protection to be effective, it needs both IP address plus hostname to match
0
 
LVL 93

Assisted Solution

by:John Hurst
John Hurst earned 250 total points
ID: 41735147
I looked quickly and will look again when I have time. If your firewall is otherwise properly locked down, open a port for one IP address only (not everyone) is not likely to cause harm.
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The 21st century solution to antiquated pagers.
The next five years are sure to bring developments that are just astonishing, and we will continue to try to find the balance between connectivity and security. Here are five major technological developments from the last five years and some predict…
To show how to create a transport rule in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Mail Flow >> Rules tab.:  To cr…
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…

825 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question