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Krishnan Subramanian | Dec 17, 2020
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Menlo Labs has uncovered a increase in a drive-by attack that impersonates legitimate browser, Flash, and Microsoft Teams updates
In the last two months, the Menlo Labs team has witnessed a surge in drive-by download attacks that use the “SocGholish” framework to infect victims. This particular framework is known to be widely used to deliver malicious payloads by masquerading as a legitimate software update. Isolation prevents this type of attack from delivering its payload to the endpoint. Here’s what we know.
A drive-by attack is when a user visits an infected website and the website triggers a malicious download without user intervention.
The term “Soc” in the “SocGholish” framework refers to the attack’s use of social engineering toolkits masquerading as a software update. Thus far, Menlo has observed this particular framework using several social engineering themes that impersonate browser updates (Chrome/Firefox), Flash Player updates, and more recently, Microsoft Teams updates.
Menlo Labs has also detected a fake Google Drive share link site that is served from an iframe on a malicious website, although the malicious ZIP file is hosted on Google Drive. The ZIP file has an embedded JScript file that, upon execution, downloads additional malware.
The following diagram depicts the typical kill chain used by the SocGholish framework:
Two key observations about the SocGholish framework within the browser context:
User interaction is still required to extract and execute the contents inside the malicious ZIP file, but this is where social engineering and trust from the source of the file comes in. Because the file is hosted in an iframe within a legitimate site, users are tricked into thinking the file is from a legitimate source and encouraged to download and execute the file.
The malicious ZIP file has an embedded JScript file that, upon execution, uses living-off-the-land binaries (PowerShell/CMD, etc.) to fetch a malicious download—providing additional command and control communication to download the final malware.
This framework is used to gain initial access to an endpoint. From past research, we’ve seen this framework distribute the Dridex Banking Trojan and variations of the WastedLocker ransomware family.
The iframes that are used to serve content from malicious sites are hosted on sites that have been categorized as legitimate categories, such as download sites or other categories in which reasonably popular websites are often hosted.
The malicious ZIP file is usually delivered from popular cloud hosting providers. The following chart shows a breakdown of the specific service providers that were used to host these malicious ZIP files.
From our analysis, we know that the drive-by download mechanisms used by the SocGholish framework did not involve any browser exploitation or exploit kits to deliver malicious payloads. Depending on the social engineering theme used, we have observed the following mechanisms used to trigger the drive-by download:
Victims are lured into visiting a reasonably popular website within the Alexa top ~100K ranking, where the attackers plant an iframe that sends users through a series of redirections to trigger the malicious download.
This mechanism is very similar to the DURI campaign we wrote about recently. Since the entire payload is constructed within the endpoint, this method is commonly used to smuggle payloads and bypass legacy network proxies and sandboxes.
This is the mechanism we observed in the sites.google.com fake share theme.
Recently, Chrome and Firefox developers have added a security feature that automatically blocks downloads from sandboxed iframes. In the above techniques, downloads were allowed from iframes specified by the following settings:
As we head into the holiday season and 2020 winds down, it’s important to be vigilant against these types of sophisticated attacks that impersonate legitimate software updates to deliver their malicious payload. Remember that many browsers, including Chrome, have automated patching and updates—eliminating the kind of prompt that SocGholish requires.
Alternatively, it may be time to think about implementing isolation—the only security technology that prevents all web-based attacks by preventing any content (risky or not) from executing on the endpoint, without impacting the native user experience. It’s simple: Malicious actors can’t infect something they can’t access. Learn more about isolation at menlosecurity.com.
Posted by Krishnan Subramanian on Dec 17, 2020
Tagged with Malware, Menlo Labs, Web Security
Threat Trends & Research
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