More Thoughts on Security

5 minute read time.


Last week I blogged on some security topics that were prompted by the Heartbleed security hole. Heartbleed was hot while it lasted, but in the end most servers were quickly patched and not a lot of damage was reported. Now this last week Heartbleed was completely pushed aside by the latest Internet Explorer security vulnerability. A lot of the drama of this problem was caused by speculation on whether Microsoft would fix it for Windows XP. Although the problem existed in all versions of Windows and IE, it was assumed that Microsoft would fix it fairly quickly for new versions of Windows, but leave Windows XP vulnerable.

The IE Problem

Microsoft’s Internet Explorer has had a history of problems with letting rogue web sites take over people’s computers by downloading and executing nasty code. The first cases of this was that IE would run ActiveX controls, which basically are compiled programs downloaded to your computer and then run in the Browser’s process space. These led to all sorts of malicious programs and viruses. First Microsoft tried to make ActiveX controls “signed” by a trusted company, but generally these caused so many problems that people have to be very careful which ActiveX controls to allow.

With ActiveX controls blocked, malicious software writers turned to other ways to get their code executed inside IE. A lot of these problems date back to Microsoft’s philosophy in the early 90s of having code execute anywhere. So they had facilities to execute code in word processing documents, and all sorts of other things. Many of the new malicious software finds old instances of this where Microsoft unexpectedly lets you run code in something that you wouldn’t expect to run code. Slowly but surely these instances are being plugged one by one through Windows Updates.

The next attack surface is to look for bugs in IE. If you’ve ever tried running an older version of IE under Bounds Checker, you would see all sorts of problems reported. Generally a lot of these allow attackers to exploit buffer overrun problems and various other memory bugs in IE to get their code loaded and executing.

Another attack surface is common plugins that seem to always be present in IE like for rendering PDF documents or for displaying Adobe Flash based websites or using Microsoft Silverlight. All these plugins have had many security holes that have allowed malicious code to execute.

Plugging these holes one by one via Windows update is a continuing process. However Microsoft has taken some proactive steps to make hacking IE harder. The have introduced things like more advanced memory protections and ways to randomize memory buffer usage to make it harder for hackers to exploit things. However they haven’t trimmed down the functionality that leads to such a large attack surface.

The latest exploit that was reported in the wild last week got around all Microsoft’s protections and allowed a malicious web site to take over any version IE on any version of Windows that browsed that site. Then the malicious web site could install software to steal information from the affected computer, install a keyboard logger to catch typed passwords or install e-mail spam generation software.

Why the Fuss?

This new exploit was a fairly typical IE exploit, so why did it receive so much attention? One reason is that after Heartbleed, security is on everyone’s mind. The second is that Microsoft has ended support for Windows XP and publicly stated it would not release any more security updates. So the thinking was that this was the first serious security flaw that wouldn’t be patched in Windows XP and havoc would result.

However Microsoft did patch the problem after a few days, and they did patch the problem on Windows XP as well. After all Windows XP still accounts for about a third of the computers browsing the Internet today. If all of these were harnessed for a Denial of Service attack or started to send spam, it could be quite serious.

People also question how serious it is since you have to actually browse to the malicious web site. How do you get people to do this? One way is when URLs expire, sometimes someone malicious can renew it and redirect to a bad place. Another way is to register URLs with small spelling mistakes from real websites and get unwary visitors that way. Another approach is to place ads on sites that just take the money without validating the legality of the ad or what it links to. Sending spam with the bad URLs is another common approach to lure people.

How to Protect Yourself

Here are a few points you can adopt to make your life safer online:

  • Use supported software, don’t use old unsupported software like Windows XP. Windows 7 is really good, at least upgrade to that. If your computer isn’t connected to the Internet then it doesn’t really matter.
  • Make sure Windows Update is set to automatically keep your computer up to date.
  • Don’t click on unknown attachments in e-mails
  • If you receive spam with a shortened or suspicious URL link, don’t click on it.
  • Go through the add-ons in your browser and disable anything that you don’t know you use regularly (including all those toolbars that get installed).
  • When browsing unfamiliar sites on the web, use a safer browser like Google Chrome. Nothing is foolproof but generally Chrome has a better history than most other browsers.
  • Make sure you have up to date virus scanning software running. There are several good free ones including AVG Free Edition.
  • Make sure you have Windows Firewall turned on.
  • Don’t run server program you don’t need. You probably don’t need to be running an FTP server or an e-mail server. Similarly don’t run a whole bunch of database servers you aren’t using, or stop them when not in use.
  • Don’t trust popup Windows from unfamiliar or suspicious websites. I.e. if suddenly a Window pops up telling you to update Java or something, it’s probably a fake and going to install something bad. Always go to a company’s main site of something you are going to install.
  • Never give personally identifiable data to unknown websites, they have no good reason to know your birthday, phone number or mother’s maiden name.
  • Don’t use the same password on all websites. For websites that you care about have a good unique password.
  • Be distrustful of URLs that are sort of right, but not quite (often it’s better to go through Google than to spell a URL directly). Often scammers setup URLs with common spelling errors of popular sites to get unsuspecting victims.


There are a lot of bad things out on the Internet. But with some simple precautions and some common sense you can avoid the pitfalls and have an enjoyable web browsing experience.