Cyber criminals have exploited several zero-day flaws in a legacy IT product developed by software firm Accellion to attack several dozen groups including Canadian airline manufacturer Bombardier.
The company confirmed that a portion of its data had been compromised after an unauthorised attacker exploited vulnerabilities in Accellion’s File Transfer Application (FTA) product. This data included confidential data relating to roughly 130 employees based in Costa Rica, as well as customers and suppliers.
In the wake of the attack, Accellion also confirmed that FTA had been targeted by cyber criminals but stressed it’s a legacy product and that customers should immediately migrate to its more up-to-date Kiteworks.
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This is a purpose-built application launched 20 years ago to allow enterprises to securely transfer large files. From roughly 300 total FTA clients, fewer than 100 were victims of the attack, with hackers siphoning away significant amounts of data from 25.
Hackers exploited several vulnerabilities in the legacy product, which will stop receiving support on 30 April 2021, in order to execute their attack. These included the following:
- CVE-2021-27101 - SQL injection via a crafted Host header
- CVE-2021-27102 - OS command execution via a local web service call
- CVE-2021-27103 - SSRF via a crafted POST request
- CVE-2021-27104 - OS command execution via a crafted POST request
Researchers with FireEye confirmed that hackers with the FIN11 group targeted FTA by exploiting these flaws to install a web shell named DEWMODE. This group is also associated with the Clop ransomware.
Starting in January 2021, the ransomware gang began sending extortion emails to the companies from which they stole data, threatening to publish this on a dark web forum. Interestingly, the group hasn’t actually deployed ransomware at any stage during this attack and has appeared primarily to extort its victims instead.
The researchers say that Clop activity in this particular attack stretches back to December 2020, when they detected multiple incidents involving the newly-discovered DEWMODE web shell being used to exfiltrate data from FTA devices.
Based on analysis, the attackers follow a strategy of escalation in demanding a ransom in exchange for not publishing the compromised data. First initial emails are sent from a free account to a limited number of addresses before hundreds of thousands are sent from and to different email accounts if there’s no response.
Although Bombardier has confirmed its data was compromised as a result of the attack, the identity of the majority of the remaining 24 victims remains unknown. The Jones Day law firm, which previously served Donald Trump, is believed to be another company targeted as part of the FTA attack, with the FIN11 group allegedly stealing 100GB of confidential files.
