Candiru surveillance spyware DevilsTongue exploited Chrome Zero-Day to target journalists

The spyware developed by Israeli surveillance firm Candiru exploited recently fixed CVE-2022-2294 Chrome zero-day in attacks on journalists.

Researchers from the antivirus firm Avast reported that the DevilsTongue spyware, developed, by Israeli surveillance firm Candiru, was used in attacks against journalists in the Middle East and exploited recently fixed CVE-2022-2294 Chrome zero-day.

The flaw, which was fixed by Google on July 4, 2022, is a heap buffer overflow that resides in the Web Real-Time Communications (WebRTC) component, it is the fourth zero-day patched by Google in 2022.

Most of the attacks uncovered by Avast researchers took place in Lebanon and threat actors used multiple attack chains to target the journalists. Other infections were observed in Turkey, Yemen, and Palestine since March 2022.

In one case the threat actors conducted a watering hole attack by compromising a website used by employees of a news agency.

The researchers noticed that the website contained artifacts associated with the attempts of exploitation for an XSS flaw. The pages contained calls to the Javascript function “alert” along with keywords like “test”, a circumstance that suggests the attackers were testing the XSS vulnerability, before ultimately exploiting it to inject the loader for a malicious Javascript from an attacker-controlled domain (i.e. stylishblock[.]com).

This injected code was used to route the victims to the exploit server, through a chain of domains under the control of the attacker.

Once the victim lands on the exploit server, the code developed by Candiru gathers more information the target system, and only if the collected data satisfies the exploit server the exploit is used to deliver the spyware.

“While the exploit was specifically designed for Chrome on Windows, the vulnerability’s potential was much wider. Since the root cause was located in WebRTC, the vulnerability affected not only other Chromium-based browsers (like Microsoft Edge) but also different browsers like Apple’s Safari.” reads the analysis published by Avast. “We do not know if Candiru developed exploits other than the one targeting Chrome on Windows, but it’s possible that they did.”

The zero-day was chained with a sandbox escape exploit, but experts were not able to recover it due to the protection implemented by the malware.

After getting a foothold on the victim’s machine, the DevilsTongue spyware attempts to elevate its privileges by exploiting another zero-day exploit. The malicious software targets a legitimate signed kernel driver in a BYOVD (Bring Your Own Vulnerable Driver) fashion. In order to exploit the the driver, it has to be first dropped to the filesystem (Candiru used the path C:\Windows\System32\drivers\HW.sys), experts pointed out that this could be used as an indicator of compromise. 

“While there is no way for us to know for certain whether or not the WebRTC vulnerability was exploited by other groups as well, it is a possibility. Sometimes zero-days get independently discovered by multiple groups, sometimes someone sells the same vulnerability/exploit to multiple groups, etc. But we have no indication that there is another group exploiting this same zero-day.” concludes the report.

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Pierluigi Paganini

(SecurityAffairs – hacking, Candiru)