Microsoft has started the year with an href="https://www.microsoft.com/en-us/WindowsForBusiness/End-of-IE-support">announcement
that, effective Jan. 12, 2016, support for all older versions of
Internet Explorer (IE) will come to an end (known as an EoL, or End of
Life). The affected versions are Internet Explorer 7, 8, 9, and 10.
What this means for users is that Microsoft will no longer release
new security updates for these product versions going forward. This
gives users two options: Internet Explorer 11 and Microsoft Edge, the
latter of which is currently exclusive to Windows 10. If users would
like to keep their browsers up to date, they will need to upgrade to
either of these two options.
It should go without saying that Internet Explorer users are
strongly encouraged to update to the latest version. It offers
improved security with the latest security features and mitigations.
Two notable mitigations introduced to the browser in 2014 are Isolated
Heap and Memory Protect, which were implemented on Patch Tuesday of
June and July 2014 respectively. Prior to that, Microsoft made a
similar announcement about the Windows XP Operating System, wherein
they issued an End of Life for XP in April 2014.
These are all steps in right direction for the Microsoft teams
because it allows for the consolidation of team efforts, resulting in
a stronger focus on securing fewer versions across a smaller code
base. Microsoft continues to silently enhance protections as the
months go by while at the same time trimming code.
Figure 1 shows the vulnerability counts for Internet Explorer
versions in 2015.

Figure 1. Internet Explorer vulnerability count
for 2015 [1]
The graph above shows the total number of reported vulnerabilities
affecting each version of Internet Explorer across the months of 2015.
Keeping in mind that these are non-unique counts, we can observe that,
for the most part, the majority of the reported vulnerabilities
affected Internet Explorer 11.
Figure 2 shows the most notable in the wild (ITW) attacks exploiting
Internet Explorer in 2014 and 2015.
Figure 2. ITW attacks of Internet Explorer [1]
The majority of the attacks found ITW in 2014 and 2015 affected IE 11.
Figure 3 compares the count of vulnerabilities that affect Internet
Explorer 11 (IE 11) to the ones that don’t.

Figure 3. IE11 vs.
Non-IE11 vulnerability count [1]
Based on the information found in Figures 1, 2, and 3, most of the
vulnerabilities reported in 2015 affected Internet Explorer 11. This
shows that attackers, as well as researchers, are focusing
considerably on Internet Explorer 11. Microsoft’s most recent move
will allow the company to do the same.
It should be noted that, as of Internet Explorer 11, some features
are no longer supported or are considered deprecated. These include,
but are not limited to, VML and VBScript, which have
been used to href="http://www.vupen.com/blog/20130522.Advanced_Exploitation_of_IE10_Windows8_Pwn2Own_2013.php">exploit
and href="https://technet.microsoft.com/en-us/library/security/ms14-064.aspx">compromise
the integrity of Internet Explorer, or leveraged to bypass ASLR/DEP in
the past. This is a strong move in the right direction, as trimming
the code base leads to shrinking the attack surface. This helps secure
products such as Internet Explorer.
It is also worth noting that at this point no ITW attacks have been
observed against Microsoft Edge, the new web browser that currently
ships exclusively with Windows 10. Microsoft Edge also follows the
same approach of removing unnecessary features such as ActiveX and
Browser Helper Objects, as well as others.
In conclusion, after Jan. 12, 2016, older Internet Explorer users
will be exposed to vulnerabilities that may be exploited by malware
and targeted by Exploit Kits. The best way to defend against this is
to keep your browser up to date by upgrading to Internet Explorer 11
or using Microsoft Edge.
[1] Microsoft Security Bulletins: https://technet.microsoft.com/en-us/library/security/dn610807.aspx