RE: OMA and Outgoing Spam
- From: v-chacez@xxxxxxxxxxxxx (chace zhang)
- Date: Fri, 22 Sep 2006 06:59:48 GMT
Hi,
Thanks for your update.
I'm glad to hear this info is helpful.
If you have additional questions, please do not hesitate to post in this
Newsgroup.
I look forward to working with you again.
Best Regards,
Chace Zhang (MSFT)
Microsoft CSS Online Newsgroup Support
Get Secure! - www.microsoft.com/security
=====================================================
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--------------------
| Thread-Topic: OMA and Outgoing Spam
| thread-index: AcbdocDHCcii64jiSOOPAKKcQbrj5g==
| X-WBNR-Posting-Host: 63.150.7.130
| From: =?Utf-8?B?RG9j?= <Doc@xxxxxxxxxxxxxxxxxxxxxxxxx>
| References: <FB2173A3-9E78-47F0-B2A9-31E74E150F8B@xxxxxxxxxxxxx>
<aB8CSE72GHA.3440@xxxxxxxxxxxxxxxxxxxxx>
<DD618CF4-DEF7-4CF5-9CA6-278C989EA41D@xxxxxxxxxxxxx>
<Ab4b2TJ3GHA.4280@xxxxxxxxxxxxxxxxxxxxx>
| Subject: RE: OMA and Outgoing Spam
| Date: Thu, 21 Sep 2006 10:17:02 -0700
| Lines: 307
| Message-ID: <1BE9EE9B-0DC0-490D-ADAC-D58AD4A54EAD@xxxxxxxxxxxxx>
| MIME-Version: 1.0
| Content-Type: text/plain;
| charset="Utf-8"
| Content-Transfer-Encoding: 7bit
| X-Newsreader: Microsoft CDO for Windows 2000
| Content-Class: urn:content-classes:message
| Importance: normal
| Priority: normal
| X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.1830
| Newsgroups: microsoft.public.windows.server.sbs
| Path: TK2MSFTNGXA01.phx.gbl
| Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.windows.server.sbs:299249
| NNTP-Posting-Host: TK2MSFTNGXA01.phx.gbl 10.40.2.250
| X-Tomcat-NG: microsoft.public.windows.server.sbs
|
| Chace,
| Thanks so much for all of the info.. I will work through it and see if
this
| fixes the problem... This is very helpful!!
| Doc
|
| "chace zhang" wrote:
|
| > Hi,
| >
| > Thank you for your update!
| >
| > Based on my experience, this issue can be any or a combined of the
| > following situations:
| >
| > 1. Someone hacked a user account and use it to spam emails;
| >
| > 2. Your Exchange server is open relaying emails;( You have checked it
| > already)
| >
| > 3. A virus or spyware inside your network is sending emails;
| >
| > 4. Your server is under RNDR Attack.
| >
| > I would like to suggest you try the following suggestions:
| >
| > A. Disable the Guest account in your SBS 2003 server and enable Stronge
| > Password Protection. You can also have your users change their
passwords.
| > Everytime when you run CEICW you will be asked for enabling password
| > policies after it ends. I suggest you enable it. You can also do that
in
| > Server Management\Users->Configure Password Policies. For more
information,
| > see:
| >
| >
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/
| > security/bpactlck.mspx
| >
| > B. Block open relay and clean up the SMTP queues by referring to the
| > following KB article:
| >
| > 324958 How To Block Open SMTP Relaying and Clean Up Exchange Server
SMTP
| > Queues
| > http://support.microsoft.com/?id=324958
| >
| > After performing the above suggestions, check if everything is OK. If
you
| > still see many unsolicted emails in the SMTP queues, you can try the
| > suggestions below:
| >
| > C. If you are using POP3 Connector for incoming emails, make sure POP3
| > Connector is not relaying emails. You should install the update
described
| > in the following KB article:
| >
| > 835734 Many unexpected outbound e-mail messages appear in the SMTP
queue in
| > http://support.microsoft.com/?id=835734
| >
| >
| > D. If you are using SMTP for incoming emails, you can install IMF
| > (Intelligent Message Filter):
| >
| >
http://www.microsoft.com/downloads/details.aspx?FamilyId=C1B08F7B-8CAF-4147-
| > B074-8C9C8F277071&displaylang=en
| >
| >
http://www.microsoft.com/technet/prodtechnol/exchange/2003/library/imfdeploy
| > .mspx
| >
| > However if you are using POP3 Connector for incoming emails, IMF will
not
| > work and you can ignore this suggestion.
| >
| > E. You can install SBS 2003 compatible antivirus or anti-spam software
on
| > your server to kill viruses. You can go to the following web page and
| > download the spyware removal tool to scan and remove any spyware on the
| > server and the problematic client computers:
| >
| > http://www.firewallguide.com/spyware.htm
| >
| >
| > F. If you find many emails are NDR emails generated by postmaster or
| > administrator of your server, your server should be under Reverse DNS
| > Attack. Nowadays spammers have a new means to avoid filters built into
many
| > systems. They take advantage of a mail systems sending of a
non-delivery
| > report (NDR) when a message cannot be delivered as addressed and
returns
| > the original contents. Since this follows the RFC standard, most all
| > servers will function this way.This is what is called a "Reverse NDR
| > attack" (RNDR). This form of attack is becoming increasingly
widespread.
| > Some users get it so badly that over 33% of their Internet messages are
| > attributed to this type of spam.The end result is the spammer has
attained
| > a new form of mail relaying. Your server''s resources are being stolen
to
| > deliver spam. You may abserve the following symptoms:
| >
| > 1. Exchange mailboxes are receiving NDR''s for mail that they did not
send.
| >
| > 2. Non delivery reports are filling the SMTP queues. Messages appear
from
| > Postmaster or "<>".
| >
| > 3. There are hundreds (sometimes thousands) of SMTP queues where there
are
| > normally just a few.
| >
| > How does a "Reverse NDR" attack work?
| >
| > Step 1 Spam email is created with the intended spam victim''s address
in
| > the sender field and a random, fictitious recipient, at your domain, in
the
| > To: field.
| >
| > Step 2 Your mail server cannot deliver the message and sends an NDR
| > back to what appears to be the sender of the original message, the spam
| > victim.
| >
| > Step 3 The return email carries the non-delivery report and possibly
the
| > original spam message. Thinking it is email they sent, the spam victim
| > reads the NDR and the included spam.
| >
| > What are the symptoms of a RNDR attack?
| >
| > 1. Sluggish email delivery
| >
| > 2. Outbound queues full of non-delivery notices
| >
| > 3. Excessive admin time to clear outbound queues
| >
| > If you are experiencing any of the above, chances are good your mail
server
| > is under attack.
| >
| > To stop the RNDR from happening, you can try either of the following
| > solutions based on your configuration:
| >
| > If you use SMTP to receive inbound emails
| > -------------------------------------
| > - Configure Recipient Filtering
| >
| > When you enable recipient filtering on the SMTP virtual server, e-mail
| > messages that are received from anyone on the recipient filter are not
| > accepted. Recipient filtering is set globally, but you enable it on a
| > per-Virtual Server basis on each SMTP virtual server.
| >
| > - Create a recipient filter:
| >
| > 1. Click "Start", point to "Programs", point to "Microsoft Exchange",
and
| > then click "System Manager".
| >
| > 2. Expand "Global Settings", right-click "Message Delivery", and then
click
| > "Properties".
| >
| > 3. Click the "Recipient Filtering" tab, and then click the checkbox at
the
| > bottom (Filter recipients who are not in the directory).
| >
| > 4. Specify any additional filter options that you want to configure,
| > Select Apply, and then click "OK".
| >
| > To enable recipient filtering on the SMTP virtual server:
| >
| > 1. Click "Start", point to "Programs", point to "Microsoft Exchange",
and
| > then click "System Manager".
| >
| > 2. Expand "Servers", expand "<ServerName>", and then expand "Protocols".
| >
| > 3. Expand "SMTP", right-click "Default SMTP Virtual Server", and then
click
| > "Properties".
| >
| > 4. Click the "General" tab, and then click "Advanced".
| >
| > 5. In the "Address" list, click the IP address where you want to apply
the
| > recipient filter, and then click "Edit".
| >
| > 6. Click to select the "Apply Recipient Filter" check box, click "OK",
and
| > then click "OK".
| >
| > Note: Recipient filter rules apply only to anonymous connections.
| > Authenticated users and Exchange servers bypass these validations.
| >
| > If you are using POP3 Connector to receive inbound emails
| > -------------------------------------
| > In this scenario, we cannot use recipient filters to stop the attack.
You
| > will have to contact your ISP to help you stop the NDR attack. Or you
will
| > need to disable the NDR feature. To do so, please refer to the
following KB
| > article:
| >
| > 294757 How to control non-delivery reports when you use Exchange 2000 or
| > http://support.microsoft.com/?id=294757
| >
| > We can also use third party tools to block NDR attack:
| >
| >
http://www.cmsconnect.com/Praetor/WebHelp/zAppendix_B_-_Message_tests/Thwart
| > ing_reverse_NDR_attacks.htm
| >
| > http://www.mapilab.com/exchange/mail_guard/
| >
| > F. You can also install third party anti-spam and antivirus software
| > however you should make sure they are fully compatible with Windows
Server
| > 2003 and Exchange Server 2003. Otherwise they may cause instability to
the
| > server. If you install antivirus software, you should exclude the
SYSVOL
| > and Exchange installation folder exchsrvr from being scanned. For more
| > information, see:
| >
| > 823166 Overview of Exchange Server 2003 and antivirus software
| > http://support.microsoft.com/?id=823166
| >
| > 822158 Virus Scanning Recommendations on a Windows 2000 Domain
Controller
| > http://support.microsoft.com/?id=822158
| >
| > NOTE: This response contains a reference to a third party World Wide
Web
| > site. Microsoft is providing this information as a convenience to you.
| > Microsoft does not control these sites and has not tested any software
or
| > information found on these sites; therefore, Microsoft cannot make any
| > representations regarding the quality, safety, or suitability of any
| > software or information found there. There are inherent dangers in the
use
| > of any software found on the Internet, and Microsoft cautions you to
make
| > sure that you completely understand the risk before retrieving any
software
| > from the Internet.
| >
| > Regarding your questions:
| >
| > 1. This is possible.
| >
| > 2. You can use message tracking against a SMTP queue to check for the
| > message trace:
| >
| > 821910 How to troubleshoot for Exchange Server 2003 transport issues
| > http://support.microsoft.com/?id=821910
| >
| > 3. Spammers have several methods to hide the original sender to spam
emails
| > and it''s hard to track the original sender. You can implement the
above
| > suggestions to block spam and unsolicited emails.
| >
| > 4. See above suggestions.
| >
| > Please do not hesitate to let me know if you have any further concerns
| >
| > Best Regards,
| >
| > Chace Zhang (MSFT)
| >
| > Microsoft CSS Online Newsgroup Support
| >
| > Get Secure! - www.microsoft.com/security
| >
| > =====================================================
| > This newsgroup only focuses on SBS technical issues. If you have issues
| > regarding other Microsoft products, you'd better post in the
corresponding
| > newsgroups so that they can be resolved in an efficient and timely
manner.
| > You can locate the newsgroup here:
| > http://www.microsoft.com/communities/newsgroups/en-us/default.aspx
| >
| > When opening a new thread via the web interface, we recommend you check
the
| > "Notify me of replies" box to receive e-mail notifications when there
are
| > any updates in your thread. When responding to posts via your
newsreader,
| > please "Reply to Group" so that others may learn and benefit from your
| > issue.
| >
| > Microsoft engineers can only focus on one issue per thread. Although we
| > provide other information for your reference, we recommend you post
| > different incidents in different threads to keep the thread clean. In
doing
| > so, it will ensure your issues are resolved in a timely manner.
| >
| > For urgent issues, you may want to contact Microsoft CSS directly.
Please
| > check http://support.microsoft.com for regional support phone numbers.
| >
| > Any input or comments in this thread are highly appreciated.
| >
| > =====================================================
| >
| > This posting is provided "AS IS" with no warranties, and confers no
rights.
| >
| >
| > --------------------
| > | Thread-Topic: OMA and Outgoing Spam
| > | thread-index: Acbb/vAKI3kd5nkCSYatOSX8yZV7sA==
| > | X-WBNR-Posting-Host: 63.150.7.130
| > | From: =?Utf-8?B?RG9j?= <Doc@xxxxxxxxxxxxxxxxxxxxxxxxx>
| > | References: <FB2173A3-9E78-47F0-B2A9-31E74E150F8B@xxxxxxxxxxxxx>
| > <aB8CSE72GHA.3440@xxxxxxxxxxxxxxxxxxxxx>
| > | Subject: RE: OMA and Outgoing Spam
| > | Date: Tue, 19 Sep 2006 08:19:02 -0700
| > | Lines: 164
| > | Message-ID: <DD618CF4-DEF7-4CF5-9CA6-278C989EA41D@xxxxxxxxxxxxx>
| > | MIME-Version: 1.0
| > | Content-Type: text/plain;
| > | charset="Utf-8"
| > | Content-Transfer-Encoding: 7bit
| > | X-Newsreader: Microsoft CDO for Windows 2000
| > | Content-Class: urn:content-classes:message
| > | Importance: normal
| > | Priority: normal
| > | X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.1830
| > | Newsgroups: microsoft.public.windows.server.sbs
| > | Path: TK2MSFTNGXA01.phx.gbl
| > | Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.windows.server.sbs:298636
| > | NNTP-Posting-Host: TK2MSFTNGXA01.phx.gbl 10.40.2.250
| > | X-Tomcat-NG: microsoft.public.windows.server.sbs
| > |
| > | Chace,
| > | Thanks so much for the response! The outgoing SPAM was discovered
using
| > the
| > | message tracking tool and noting a great deal of activity
after-hours. I
| > | really have no way of seeing the actual email message as the SPAM
appears
| > to
| > | be spoofing the user in question, i.e., the "from" and "to" fields
are
| > the
| > | same yet the message is being sent via SMTP to njbrwigsp2-13 (can be
any
| > | server with this name from 2 to 13). I've got recipient filtering
| > established
| > | and I also have the relay option turned off. Additionally I'm running
the
| > IMF
| > | on all inbound mail...
| > |
| > | Thanks again!
| > | Doc
| > |
| > | "chace zhang" wrote:
| > |
|
.
- References:
- RE: OMA and Outgoing Spam
- From: chace zhang
- RE: OMA and Outgoing Spam
- From: Doc
- RE: OMA and Outgoing Spam
- From: chace zhang
- RE: OMA and Outgoing Spam
- From: Doc
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