Exploitation is a Dish Best Served Cold: Winter Vivern Uses Known Zimbra Vulnerability to Target Webmail Portals of NATO-Aligned Governments in Europe
- Proofpoint has observed recent espionage-related activity by TA473, including yet to be reported instances of TA473 targeting US elected officials and staffers. TA473 is a newly minted Proofpoint threat actor that aligns with public reporting on Winter Vivern. * TA473 since at least February 2023 has continuously leveraged an unpatched Zimbra vulnerability in publicly facing webmail portals that allows them to gain access to the email mailboxes of government entities in Europe. * TA473 recons and reverse engineers bespoke JavaScript payloads designed for each government targets’ webmail portal. * Proofpoint concurs with Sentinel One analysis that TA473 targeting superficially aligns with the support of Russian and/or Belarussian geopolitical goals as they pertain to the Russia-Ukraine War.