(Since this story was published, the VMware ESXi server ransomware evolved, after a recovery script was released.)\n\nA global ransomware attack has hit thousands of servers running the VMware ESxi hypervisor, with many more servers expected to be affected, according to national cybersecurity agencies and security experts around the world.\n\nThe Computer Emergency Response Team of France (CERT-FR) was the first to notice and send an alert about the attack.\n\n\u201cOn February 3, CERT-FR became aware of attack campaigns targeting VMware ESXi hypervisors with the aim of deploying ransomware on them,\u201d CERT-FR wrote. \n\nOther national cybersecurity agencies \u2014 including organizations in the US, France and Singapore \u2014 have also issued alerts about the attack. Servers have been compromised in France, Germany, Finland, the US and Canada, according to reports.\n\nMore than 3,200 servers have been compromised globally so far, according to cybersecurity firm Censys.\n\nCERT-FR and other agencies report that the attack campaign exploits the CVE-2021-21974 vulnerability, for which a patch has been available since February 23, 2021. This vulnerability affects the Service Location Protocol (SLP) service and allows attackers to exploit arbitrary code remotely. The systems currently targeted are ESXi hypervisors in version 6.x, prior to 6.7, CERT-FR stated. \n\n\u201cThe SLP can be disabled on any ESXi servers that haven\u2019t been updated, in order to further mitigate the risk of compromise,\u201d CERT-FR wrote in its notice. \n\nAn alert from cybersecurity provider DarkFeed over the weekend said that in Europe, France and Germany were most affected by the attack. Most of the servers that were hit in France and Germany were being hosted by hosting providers OVHcloud and Hetzner, respectively, according to DarkFeed.\n\nA ransom note issued to the victims of the attack posted publicly by DarkFeed said in part: "Security alert! We hacked your company successfully ... Send money within 3 days, otherwise we will expose some data and raise the price."\n\nThe note quoted by DarkFeed said to send 2.01584 (about US$23,000) to a bitcoin wallet, but apparently the threat actor is using different wallets to collect fees. \u201cWhat's interesting is that the bitcoin wallet is different in every ransom note. No website for the group, only TOX id,\u201d DarkFeed stated. \n\nSecurity agencies globally are offering advice to security teams.\n\nAdministrators advised to update to latest ESXi version\n\n\u201cUsers and administrators of affected product versions are advised to upgrade to the latest versions immediately. As a precaution, a full system scan should also be performed to detect any signs of compromise. Users and administrators are also advised to assess if the ransomware campaign-targeted port 427 can be disabled without disrupting operations,\u201d the Singapore Computer Emergency Response Team (SingCERT), said in a notice. \n\nSecurity researchers have been analyzing the attacks since they came to light, issuing similar advice and adding information.\n\n\u201cUpgrade to the latest version of #ESXi and restrict access to the #OpenSLP service to trusted IP addresses,\u201d security researcher Matthieu Garin recommended in a Twitter post. Garin also offered information that can be useful to help recover ransomed files. "The attackers only encrypt the config files, and not the vmdk disks where the data is stored. This can definitely be very useful!,\u201d Garin said.\n\nMeanwhile, US agencies said they were assessing the impact of the reported incidents.\n\n"CISA is working with our public and private sector partners to assess the impacts of these reported incidents and providing assistance where needed," the US Cybersecurity and Infrastructure Security Agency said in a note to media, according to Reuters.\u00a0\n\nRansomware attackers often target developed countries, researchers noted.\n\n\u201cDeveloped countries are often targeted more frequently for ransomware attacks because they have more resources and access to bitcoins and are more likely to pay the ransom demands,\u201d said Rahul Sasi, co-founder and CEO at cybersecurity firm CloudSEK.\n\n\u201cThese countries also tend to have a higher density of valuable targets, such as large corporations and government agencies, that can be impacted by a successful attack. Additionally, developed countries often have more advanced technology infrastructure, making them a more attractive target for cybercriminals looking to exploit vulnerabilities,\u201d Sasi added.