The recently released Microsoft Security Intelligence Report highlights the vast improvements in security from Windows XP to Windows 7. Even so, no operating system is perfect. I asked security experts what they think about Windows 7 security and came up with a list of what Microsoft got right and where Microsoft is still missing the mark.
A Step in the Right Direction
Microsoft made significant changes to how it protects the Windows operating system kernel and added a number of new security controls when it transitioned from Windows XP to Windows Vista. With Windows 7, many of those security controls are enhanced and there are some new features as well.
1. ASLR and DEP. ASLR (Address Space Layout Randomization) and DEP (Data Execution Prevention) both existed in Windows Vista, but have been improved for Windows 7. ASLR makes it more complicated for attackers to determine where core functions reside in memory, and DEP prevents buffer overflow attacks from working on files or in storage areas that are specifically intended to hold data.
Sophos Senior Security Advisor Chet Wisniewski says ” ASLR was massively improved in Windows 7. This means that libraries (DLL’s) are loaded into random memory addresses each time you boot. Malware often depends on specific files being in certain memory locations and this technology helps stop buffer overflows from working properly.”
Wisniewski also notes that DEP now protects Internet Explorer and other key Windows services that were not protected by DEP in Windows Vista.
2. BitLocker-to-Go. Microsoft added BitLocker drive encryption in Windows Vista. Originally it was only capable of encrypting the partition that Windows was actually installed on, but the functionality was expanded with Service Pack 1 to include additional partitions or volumes–but not portable storage.
Tyler Reguly, Lead Security Research Engineer with nCircle, notes that with Windows 7, Microsoft has included the ability to encrypt data on USB thumb drives. Reguly says that with the popularity of USB thumb drives–capable of holding gigabytes of data–“the expansion of BitLocker to include removable drives should be counted as a significant enhancement.”
3. IE8. Internet Explorer 8 is not specific to Windows 7–users of other Windows operating systems are also free to download and use the new Web browser. But, both Reguly and Wisniewski agree that it should go on the list.
Tyler Reguly commented that “The release of IE8 makes it evident that Microsoft is starting to take browser security seriously.”
Sophos’ Wisniewski elaborated more, explaining that IE8 “includes a new protection called SmartScreen which is similar to the protection in Google Chrome and Mozilla Firefox. This anti-phishing/anti-malware URL filtering is built into the browser, which can block known bad sites and helps protect users.”
In addition, IE8 highlights the actual domain of the URL in bold on the address bar. The added emphasis makes the true domain stand out and can act as a phishing deterrent by alerting the user when a fake or malicious URL may be directing them to a different domain than they were expecting.
More Work to Be Done
As far as Microsoft has come with security, its not perfect. No operating system ever will be. Still, it can’t hurt to try so here is a look at some of the areas that Windows 7 is lacking and perhaps some ideas for Microsoft to work on for Windows 8.
1. Windows Firewall. The Windows Firewall is an area where Microsoft has come a long (long) way from its original attempt at incorporating personal firewall protection into the operating system. One of the primary complaints about earlier versions was that it only restricted inbound traffic and did not provide any mechanism for blocking or filtering traffic outbound from the Windows PC. Microsoft has addressed that.
nCircle’s Tyler Reguly says “As a personal choice, I won’t use third-party firewall software. I find them to be too resource-intensive and too much of a pain. So, I would love it if the Windows Firewall was more powerful.”
I should note, though, that perhaps there is a correlation between “more powerful” and “resource-intensive”. Perhaps the reason third-party personal firewalls eat up more resources is related to the more comprehensive protection they provide.
This may be an area where Microsoft simply needs to strike the right balance between security and performance.
2. Hidden File Extensions. Microsoft continues to hide known file extensions by default. In other words, rather than displaying a full file name like ‘pcworld.docx’, Windows will only display ‘pcworld’.
The idea is to make things more simple or user-friendly. We don’t want to confuse the end-user with frivolous details like ‘docx’, or ‘xls’, or ‘mp3’.
Chet Wisniewski points out, though, that hiding the file names is a security concern as well. He says that hiding file extensions “makes it much easier for email Trojans to use double extensions to trick users into launching their payload. Files named FinancialStatement.doc.exe will appear to the user as FinancialStatement.doc with an EXE icon.”
The operative concern here, though, is that it is a complete Windows XP environment that is not protected in any way by the Windows 7 security controls. Wisniewski explains “Windows XP Mode introduces another layer of complexity for securing a Windows desktop. Because a total virtual machine (VM) is running on your PC that requires you to run a full security suite within that VM and manage that appropriately.”
Wisniewski also notes that “By default Windows auto-maps drives from your XP virtual machine to your Windows 7 machine. This could be a major malware vector if not properly protected.”
The ever-popular UAC (User Account Control) gets an honorable mention as a pro and a con. Although it has been both presented and perceived as a security control, UAC is more about enforcing sound software development practices. Security is sort of a fringe benefit.
Tyler Reguly likes the changes Microsoft has made for UAC with Windows 7. “The decreased interruptions will mean more people will leave UAC on, this is definitely a benefit. It ends up being more functionality, less security, but can still be seen as an improvement in security overall.”
Chet Wisniewski counters by pointing out that UAC is not really a security function in the first place, but also comments that ” Microsoft does need to continue to use UAC to encourage developers to follow proper privilege separation models, because this can help Microsoft make a more secure Windows, but it should not be positioned as a feature to the end-user.”