A note on Group Policy and gpudate

When I first started learning about Active Directory, Group Policy always seemed very fickle. Sometimes I could run GPUpdate, other times I had to append the /force option.


As it turned out, Group Policy was always working –  I just didn’t understand it. So what’s the difference between GPUpdate and GPUpdate /force? Well –

GPUpdate: Applies any policies that is new or modified

GPUpdate /force: Reapplies every policy, new and old.

So which one should I use? 99% of the time, you should only run gpupdate. If you just edited a GPO and want to see results immediately, running gpupdate will do the trick. In fact, running GPUpdate /force on a large number of computers could adversely affect network resources. This is because these machines will hit a domain controller and reevaluate every GPO applicable to them.

Notice the Group Policy Update option for OUs:



How Attackers Use a Flash Exploit to Distribute Malware

Adobe Flash is multimedia software that runs on more than 1 billion systems worldwide. Its long list of security vulnerabilities and huge market presence make it a ‘target-rich environment’ for attackers to exploit. According to Recorded Future, from January 1, 2015 to September 30, 2015, Adobe Flash Player comprised eight of the top 10 vulnerabilities leveraged by exploit kits.

Here is an illustration of just how quickly bad actors can deploy an exploit:

  • May 8 2016: FireEye discovers a new exploit targeting an unknown vulnerability in Flash and reports it to Adobe.
  • May 10 , 2016: Adobe announces a new critical vulnerability (CVE-2016-4117) that affect Windows, Macintosh, Linux, and Chrome OS
  • May 12, 2016: Adobe issues a patch for the new vulnerability (APSB16-15)
  • May 25, 2016: Malwarebytes Labs documents a ‘malvertising’ gang using this exploit to compromise your system via distribution of malware well-known websites and avoid detection

The Malwarebytes blog is a good read, as it provides several examples of how sophisticated malware distribution schemes have become. For example, it breaks down the malicious elements of a rogue advertising banner that the Flash exploit allows attackers to use to push out malware. Among other things, it runs a series of checks to see if the targeted system is running packet analyzers and security technology, to ensure that it only directs legitimate vulnerable systems to the Angler Exploit Kit.

Impact on you

With over 1 billion systems running Adobe Flash, it is likely that one or more systems under your control are vulnerable to this exploit. Fortunately, there is a fix to patch the vulnerability. Unfortunately, according to Adobe, it takes 6 weeks for more than 400 million systems to update to a new version of Flash Player. Six weeks (or however long it takes you to patch Flash) is a long time to be at risk of being compromised by ransomware via the Angler EK.