Short Bytes: Cybellum security researchers have uncovered a new attack mechanism that can be used to take control of your antivirus and turn it into a malware. Called DoubleAgent, this attack exploits an old and undocumented vulnerability in Windows operating system. This Zero Day code injection technique affects all major antivirus vendors and has the power to hijack permissions.

T

he security researchers from Cybellum have found a new technique that can be used by the cybercriminals to hijack your computer by injecting malicious code. This new Zero-Day attack can be used to take full control over all the major antivirus software. Instead of hiding from the antivirus, this attack takes control of the antivirus itself.

Called DoubleAgent, this attack makes use of a 15-year-old legitimate feature of Windows (read vulnerability)–that’s why it can’t be patched. It affects all versions of Microsoft Windows. Cybellum blog mentions that this flaw is still unpatched by most antivirus vendors. Cybellum has also tested the attack and reported it to all major antivirus vendors. But, so far only Malwarebytes and AVG have issued a patch. Trend Micro is planning to push a release in upcoming weeks.

The list of affected vendors are:

Avast

AVG

Avira

Bitdefender

Trend Micro

Comodo

ESET

F-Secure

Kaspersky

Malwarebytes

McAfee

Panda

Quick Heal

Norton

In an email sent to Fossbytes, an Avast representative claimed that Avast and AVG 2017 aren’t vulnerable. Here’s the complete statement:

“We were alerted by Cybellum last year through our Bug Bounty program to a potential self-defense bypass exploit. We implemented the fix at the time of reporting and therefore can confirm that both the Avast and AVG 2017 products, launched earlier this year, are not vulnerable. It is important to note that the exploit requires administrator privileges to conduct the attack which is difficult for hackers to achieve. Therefore, in this context, we consider the likelihood of such an attack to be low and Cybellum’s emphasis on the risk of this exploit to be overstated.”

How does DoubleAgent attack work?

Some of you might be knowing about Microsoft Application Verifier. It’s a Windows tool that comes loaded with all the versions of Microsoft Windows. Whenever an application tries to run, Application Verifier verifies it.

Cybellum researchers discovered an undocumented ability that can allow an attacker to inject a custom verifier into any application. By doing so, the attacker can gain complete control over the computer. This attack gives an attacker the ability to inject any DLL into any process. This ad injection takes place extremely early during the victim’s boot process.

DoubleAgent can even continue injecting code after reboots. This makes it a perfect persistency technique. Even if the victim would completely uninstall and reinstall the program, the attacker’s DLL would still be injected when the process executes.

If we talk about the attack vector that targets antivirus software, DoubleAgent has the ability to turn an antivirus into malware, modify the internal behavior of an antivirus, modify the trusted nature of an antivirus, destroy the system, or denial of service.

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Apart from targeting the antivirus, the other attack vectors deal with installing persistent malware, hijacking permissions, altering process behavior, attacking other user sessions, etc.

You can find more technical details about DoubleAgent on Cybellum’s website. The DoubleAgent source code is available on GitHub.

Cybellum researchers have mentioned that the fix for the vendors is to adopt Microsoft’s newer design concept called Protected Processes. But, this mechanism has only been implemented in Windows Defender.

Taking control over Norton Antivirus:

Taking control over Avira Antivirus:

Taking control over Comodo Antivirus:

Note: This story has been updated to include Avast’s official statement.