11 June 2016

During my test of AppGuard some new variants of ransomware showed up in the wild.

ReaQta reported a new and massive worldwide Locky ransomware spam campaign. The new variant downloads the payload in encrypted form from the attacker’s command and control server and decrypts it before execution on the victim’s system. This makes it harder for traditional anti-malware systems to identify the payload as malicious.

Since the decrypted version is executed from User Space AppGuard blocks the execution.

Microsoft reported a new variant called ZCryptor which behaves like a worm:

‘ZCryptor can initially infect targets through traditional phishing schemes, macros or fake installers, but also has the ability to place autorun files on removable storage devices. can initially infect targets through traditional phishing schemes, macros or fake installers, but also has the ability to place autorun files on removable storage devices. This means the ransomware can spread itself to other machines on portable storage devices, rather than relying on more targets to fall victim to phishing, according to Microsoft’s security advisory.’

I had to deactivate all Windows 10 security features on my test system to download the malware sample from malwr.com to the User Space of my account:

AppGuard runs out-of-the-box in protection mode Protected with default User Space settings.

Again, AppGuard blocked the execution of z_crypt.exe, thus prevented the malware from becoming persistent and from encrypting my documents:

AppGuard stops ZCryptor

Even if one receives ZCryptor on a portable device AppGuard will block the execution due to the default Removable Media rule:

AppGuard Removable Media default rule

More about AppGuard next week.

Have a good weekend.