Microsoft security experts are sounding the alarm on a new malware threat that uses an old but devious method to implant its code onto victims’ computers.
It seems that the malware operators behind SolarMarker are finding new success with an old trick called “SEO poisoning.” Basically, according to Microsoft, this involves “stuffing” thousands of PDF documents with SEO keywords and links which start a cascade of redirections that eventually leads the unsuspecting user to malware. “The attack works by using PDF documents designed to rank on search results,” Microsoft Security Intelligence explained on Twitter in recent days. “To achieve this, attackers padded these documents with >10 pages of keywords on a wide range of topics, from ‘insurance form’ and ‘acceptance of contract’ to ‘how to join in SQL’ and ‘math answers.'”
Microsoft continues by pointing to an eSentire blog post, which noted that these attackers have in the past used Google sites to host these infected documents, while in recent campaigns Microsoft researchers have noticed the attackers shift to Amazon Web Services and Strikingly.
Operators of the malware known as SolarMarker, Jupyter, other names are aiming to find new success using an old technique: SEO poisoning. They use thousands of PDF documents stuffed w/ SEO keywords and links that start a chain of redirections eventually leading to the malware.
— Microsoft Security Intelligence (@MsftSecIntel) June 11, 2021
Here’s how eSentire, which is a cybersecurity vendor, explains the way the process has worked, at least in recent weeks:
Business professionals are “being lured to hacker-controlled websites, hosted on Google Sites, and inadvertently installing a known, emerging Remote Access Trojan (RAT) … The attack starts with the potential victim performing a search for business forms such as invoices, questionnaires, and receipts.” The campaign, eSentire continues, lays out traps using Google search redirection, and once the RAT has been activated on a victim’s computer, “the threat actors can send commands and upload additional malware to the infected system,” including ransomware.
Microsoft notes that SolarMarker, the malware mentioned above, is a backdoor malware that steals data and credentials from browsers. This is yet another devious threat to be aware of — and another reminder to make sure you’re running the latest version of your operating software that includes the most up-to-date security measures — given that Microsoft has said this so-called “SEO poisoning” technique seems to be pretty effective. That’s evident, because Microsoft Defender Antivirus continues to detect and block “thousands of these PDF documents in numerous environments,” according to the company.
eSentire manager of threat intelligence Spence Hutchinson told ThreatPost in April that security leaders and their teams need to know that the group behind SolarMarker has gone to a lot of trouble to compromise business professionals, “spreading a wide net and using many tactics to successfully disguise their traps.”