When to Use an IIS Self Signed Certificate

SSL is an essential part of securing your IIS 7.0 site and creating a self-signed certificate in IIS 7
is much easier to do than in previous versions of IIS. SSL certificates enable the encryption of all
traffic sent to and from your IIS web site, preventing others from viewing sensitive information.
It uses public key cryptography to establish a secure connection. This means that anything
encrypted with a public key (the SSL certificate) can only be decrypted with the private key and
vice versa.
When to Use an IIS Self Signed Certificate
Never use a self signed certificate on an e-commerce site or any site that transfers valuable
personal information like credit cards, social security numbers, etc.
An SSL certificate has multiple purposes: distributing the public key and, when signed by a
trusted third-party, verifying the identity of the server so clients know they aren’t sending their
information (encrypted or not) to the wrong person. A self signed certificate is a certificate that is
signed by itself rather than a trusted third party. This means you can't verify that you are
connecting to the right server because any attacker can create a self signed certificate and launch
a man-in-the-middle attack. Because of this, you should almost never use a self signed certificate
on a public IIS server that requires anonymous visitors to connect to your site. However, self
signed certificates can be appropriate in certain situations:
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Self signed certificates can be used on an intranet. When clients only have to go
through a local intranet to get to the server, there is virtually no chance of a man-in-themiddle attack.
Self signed certificates can be used on an IIS development server. There is no need to
spend extra cash buying a trusted certificate when you are just developing or testing an
application.
Self signed certificates can be used on personal sites with few visitors. If you have a
small personal site that transfers non-critical information, there is very little incentive for
someone to attack the connection.
Just keep in mind that visitors will see a warning in their browsers (like the one below) when
connecting to an IIS site that uses a self signed certificate until it is permanently stored in their
certificate store. Never use a self signed certificate on an e-commerce site or any site that
transfers valuable personal information like credit cards, social security numbers, etc.
Generate Your IIS Self Signed Certificate
Now you know when to use an IIS self signed certificate and when not to. Now let’s create one:
(Click here to hide or show the images)
1. Click on the Start menu, go to Administrative Tools, and click on Internet Information
Services (IIS) Manager.
2. Click on the name of the server in the Connections column on the left. Double-click on
Server Certificates.
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3. In the Actions column on the right, click on Create Self-Signed Certificate...
4. Enter any friendly name and then click OK.
5. You will now have an IIS Self Signed Certificate valid for 1 year listed under Server
Certificates. The certificate common name (Issued To) is the server name. Now we just
need to bind the Self signed certificate to the IIS site.
Bind the Self Signed Certificate
1. In the Connections column on the left, expand the sites folder and click on the website
that you want to bind the certificate to. Click on Bindings... in the right column.
2. Click on the Add... button.
3. Change the Type to https and then select the SSL certificate that you just installed. Click
OK.
4. You will now see the binding for port 443 listed. Click Close.
5. Now let's test the IIS self signed certificate by going to the site with https in our browser
(e.g. https://site1.mydomain.com). When you do, you should see the following warning
stating that "The security certificate presented by this website was issued for a different
website's address" (a name mismatch error).
This is displayed because IIS always uses the server's name (in this case WINPABODPHV6W3) as the common name when it creates a self signed certificate. This
typically doesn't match the hostname that you use to access the site in your browser
(site1.mydomain.com). For many situations where IIS self signed certificates are used,
this isn't a problem. Just click "Continue to this web site" each time. However, if you
want to completely get rid of the error messages, you'll need to follow the next two steps
below.
Generate a Self Signed Certificate with the Correct Common
Name
This step is only required if you want to get rid of the warning message displayed because the
common name on the self signed certificate doesn't match the website's hostname. In order to
resolve this problem, we'll need to create the self signed certificate using the same method that is
used to create a self signed certificate in IIS 6.0 (with SelfSSL instead of through IIS).
1. Download the Internet Information Services (IIS) 6.0 Resource Kit Tools and install
SelfSSL 1.0 (if you do a Custom install you can uncheck everything except for SelfSSL).
Once it is installed, click on the Start menu, go to IIS Resources, then SelfSSL, and run
SelfSSL.
2. Paste in the following command and replace site1.mydomain.com with the hostname of
your IIS site. If you receive the erorr "Error opening metabase: 0x80040154", just ignore
it. We will be manually binding the certificate to the website.
SelfSSL /N:CN=site1.mydomain.com /V:1000
3. After the command is finished, you will have an IIS self signed certificate with the
correct common name listed in the Server Certificates section of IIS. Now follow the
instructions above to bind the certificate to your IIS website.
4. After you have bound the new certificate to your IIS site, visit it with https in your web
browser and you will encounter another error: "The security certificate presented by this
website was not issued by a trusted certificate authority." (the SSL Certificate Not
Trusted error)
Don't worry; this is the last error we will need to fix. This is a normal error for self signed
certificates because the certificate is signed by itself instead of a trusted SSL provider.
All visitors to the site will see that error unless they import the self-signed certificate into
their Trusted Root Certification Authorities store (or the appropriate SSL certificate store
for the browser they are using). You can easily add the IIS self signed certificate to the
store on the server by following the the instructions below. If you need to import the
certificate on another Windows machine, just follow the instructions on how to Move or
copy an SSL certificate from a Windows server.
Add the Self Signed Certificate to Trusted Root Certificate
Authorities
1. Click on the Start menu and click Run.
2. Type in mmc and click OK.
3. Click on the File menu and click Add/Remove Snap-in...
4. Double-click on Certificates.
5. Click on Computer Account and click Next.
6. Leave Local Computer selected and click Finish.
7. Expand the Certificates item on the left and expand the Personal folder. Click on the
Certificates folder and right-click on the self signed certificate that you just created and
select Copy.
8. Expand the Trusted Root Certification Authorities folder and click the Certificates folder
underneath it. Right-click in the white area below the certificates and click Paste.
9. Now you can visit your site with https in your web browser and you shouldn't receive any
errors because Windows will now automatically trust your IIS self signed certificate.