CVE-2019-18935

CVE-2019-18935 is a .NET deserialization vulnerability in the Progress Telerik user interface (UI) for ASP.NET AJAX, located in Microsoft's Internet Information Services (IIS) web server. This flaw in software design or implementation was exploited by multiple cyber threat actors, including an Advanced Persistent Threat (APT) actor. The vulnerability allowed these malicious entities to compromise the system, leading to potential data breaches and unauthorized access. The US Cybersecurity and Infrastructure Security Agency (CISA) disclosed this information as part of their cybersecurity advisory efforts. CISA plays a critical role in strengthening the nation’s cybersecurity capabilities and coordinating cybersecurity communications across different sectors. The disclosure regarding CVE-2019-18935 was intended to alert organizations about the potential risks and encourage them to take necessary precautions to secure their systems. The Federal Civilian Executive Branch (FCEB) was compromised from November 2022 to January 2023 due to this vulnerability. Threat actors were able to exploit the .NET deserialization Telerik vulnerability, causing significant security concerns. The incident underscores the importance of regular patching and updating of software to prevent exploitation of known vulnerabilities, and highlights the need for robust cybersecurity measures to protect against sophisticated attacks.