Pierluigi Paganini April 16, 2019

Scranos is a powerful cross-platform rootkit-enabled spyware discovered while investigating malware posing as legitimate software like video players, drivers and even anti-virus products.

The Scranos rootkit malware was first discovered late last year when experts at Bitdefender were analyzing a new password- and data-stealing operation leveraging around a rootkit driver digitally signed with a stolen certificate. 

Despite the level of sophistication of the threat, the rootkit appears to be a work in progress, experts pointed out that it is continually evolving.”

“Last year, the Bitdefender Cyber Threat Intelligence Lab started analysis of a new password- and data-stealing operation based around a rootkit driver digitally signed with a possibly stolen certificate. The operation, partially described in a recent article by Tencent, primarily targeted Chinese territory until recently, when it broke out around the world.” reads the report published by Bitdefender. Despite the sophistication, this attack looks like a work in progress, with many components in the early stage of development. Although the campaign has not reached the magnitude of the Zacinlo adware campaign, it is already infecting users worldwide.”

Scranos implements a modular architecture, with many components in the early stage of development. Experts reported that it is already infecting users worldwide. It implements features to Extract cookies and steal login credentials from multiple browsers (Google Chrome, Chromium, Mozilla Firefox, Opera, Microsoft Edge, Internet Explorer, Baidu Browser and Yandex Browser), steal a user’s payment accounts from his Facebook, Amazon and Airbnb webpages, send friend requests to other accounts and phishing messages using the victim’s Facebook account, it could share malicious APKs, steal login credentials for the user’s account on Steam, as well as download and execute any payload.

The malware is also able to inject JavaScript adware in Internet Explorer, install Chrome/Opera extensions to inject JavaScript adware on these browsers as well, exfiltrate browsing history, silently display ads or muted YouTube videos to users via Chrome, and subscribe users to YouTube video channels.

The malware spreads via Trojanized applications disguised as cracked software, or applications posing as legitimate software such as video players, drivers or even antivirus software. When executed, a rootkit driver is installed to hide the malware and ensure persistence, then it connects the C2 to download and install additional components.

Most of the infections have been observed in India, Romania, Brazil, France, Italy, and Indonesia. According to the experts, the operation is in a consolidation stage, first samples date back to November 2018, with a massive spike in December and January.

“The dropper, which doubles as a password stealer, installs a driver that provides persistence to all other components to be installed in the future. As this paper was written, the digital signature of the driver, issued to Yun Yu Health Management Consulting (Shanghai) Co., Ltd, had not been revoked on grounds of obvious fraudulent activity.” continues the repor.t

“The rootkit registers a Shutdown callback to achieve persistence. At shutdown, the driver is written to disk, and a start-up service key is created in the Registry,”

Below the infection process described by the experts:

• The dropper steals cookies, login credentials and payment info with the help of specialized DLLs. It supports the most common browsers and targets Facebook, YouTube, Amazon and Airbnb. Data gathered is sent back to the C&C.
• The dropper installs the rootkit.
• The rootkit registers a Shutdown callback to achieve persistence. At shutdown, the driver is written to disk and a start-up service key is created in the Registry.
• The rootkit injects a downloader into a svchost.exe process.
• The downloader sends some info about the system to the C&C and receives download links.

The experts also shared technical details on payloads involved in the campaign:

Extension Installer Payload — This payload installs adware extensions in Chrome used to inject adware scripts in web pages visited by the user.

Browsing History Stealer Payload — This payload collects Chrome’s browsing history and sends it to the C&C in an encrypted form. The data sent to the C2 is encrypted with AES. The main dropper is able to steal browser cookies and login credentials from Google Chrome, Chromium, Mozilla Firefox, Opera, Microsoft Edge, Internet Explorer, Baidu Browser and Yandex. It can also steal cookies and login info from victims’ accounts on Facebook, YouTube, Amazon, and Airbnb.

YouTube subscriber payload — It is basically an adware file that manipulates YouTube pages by using Chrome in debugging mode. Some droppers even install Chrome if it is not installed on the infected machine. The payload hides the Chrome window on the desktop and taskbar, but its process is visible in Task Manager/Process Explorer. The operations are performed through debug commands.

Further technical details on other payloads such as the YouTube subscriber payload, the Facebook Spammer Payload, and the Android Adware App are included in the report published by Bitdefender.

The report also includes the IoCs for this last campaign.

Pierluigi Paganini

(SecurityAffairs – scranos malware, malware)

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