[ADVISORY] Scripting Vulnerabilities in Indian Email Providers Put Millions At Risk

[S G Masood <sgmasood () yahoo com>]

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[ADVISORY] Scripting Vulnerabilities in Indian Email Providers Put Millions At Risk
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I. ABSTRACT:

The email services of several big Indian portals are susceptible to scripting attacks i.e., malicious code can be 
embedded by attackers into email messages, that, when received by unsuspecting users, can cause harmful effects. The 
services are Rediffmail.com, Indiatimes.com, Sify.com. The combined user base of these services runs into millions and 
all of these users are vulnerable. I've known about most of these vulnerabilities for years now and I am now releasing 
them because many are being massively exploited in the wild. All attempts to contact the vendors were unfruitful.


II. DESCRIPTION AND IMPACT:

It is possible to embed malicious scripts in an ordinary email to users of these services because of certain flaws in 
their anti-scripting filters. Since, these filters are not as robust as the filters used by service providers like 
Yahoo and Hotmail, many more flaws, similar to those detailed here, are undoubtedly present in these services. Some of 
the attacks possible through exploitation of these flaws -


1. User names and passwords can be stolen. Spoofed login pages are one of the many methods to do so.

2. Webpages belonging to the portals can be spoofed, including the shopping cart system.

3. Any action that the legitimate user can take can also be taken by the malicious code. Cookies can be stolen.

4. Malicious programs can be executed when combined with browser vulnerabilities.

5. Force-feeding websites to users. Spammers, phishers and scammers can redirect users to their own pages.

6. A malicious worm can be created which can traverse through the entire user base and cause destruction.

7. Users can be locked out of their inboxes. 



III. TECHNICAL DETAILS AND PROOFS OF CONCEPT:


i.Rediffmail(http://rediffmail.com):
-------------------------------------


Rediffmail has the most robust security system among all three. However, it is still susceptible to several attacks -

First vuln: Using a &#13 character as demonstrated below -

<input style=background-image:url(jav&#13;ascript:alert(document.cookie))>Hello!</input>

Second vuln: This service is also susceptible to a script insertion method previously found by 
Greymagic(http://www.greymagic.com/security/advisories/gm005-mc/). This method uses the HTML+TIME feature of IE. Here 
is an example(adapted from the Greymagic PoC) - 

<?xml:namespace prefix=t ns=urn:schemas-microsoft-com:time />
<?import namespace=t implementation=#default#time2>
<span><t:set attributeName=innerHTML to="Nuttin &lt;script defer&gt;alert(&quot;Alert!&quot;)&lt;/script&gt;" /></span>



ii. Indiatimes Mail(http://email.indiatimes.com):
--------------------------------------------------

Indiatimes email does not have a scripting filter in place. This means all HTML tags including scripts can be embedded 
into the email without any security obstacles. Example:

<script>
location.replace("http://google.com";)
</script>


iii. Sify Mail(http://mail.sify.com):
--------------------------------------



First Vuln: Server side filtering code removes everything between and including the <script> tags in the message body.

A newline character or a space character before the ">" in <script> and </script> evades filtering.


<script >
location.href="http://google.com";
</script >


Second Vuln: There is no filtering in the subject line. Html tags can also be inserted into the subject line of the 
mail which are then interpreted by the browser. Even <script> can be inserted.


Interesting - Sending "<!--" in a subject line to a user can lock them out of their inboxes.



IV. VENDOR STATUS:

Several unsuccessful attempts have been made to contact the vendors. Emails alerts did not receive responses.


V. CREDIT:

The vulnerabilities and PoCs have been discovered by S.G.Masood(sgmasood () yahoo com and sgmasood () gmail com) from 
Hyderabad, India.


VI. DISCLAIMER:

This advisory is meant only for the dissemination of information, alerting the general public about a security issue. 
Use this information at your own discretion.

In brief, the author is not responsible for any use, misuse, abuse of this information. Also, this information is 
provided "as is" without any warranty of any kind. 




*PHEW*

EOF





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