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CVE-2019-18935: Progress Telerik UI for ASP.NET AJAX Deserialization of Untrusted Data Vulnerability

CVE-2019-18935 is rated critical with a CVSS v3.1 base score of 9.8 and affects Progress Telerik UI for ASP.NET AJAX. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means exploitation in the wild has been observed.

Vulnerability description

Progress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization vulnerability in the RadAsyncUpload function. This is exploitable when the encryption keys are known due to the presence of CVE-2017-11317 or CVE-2017-11357, or other means. Exploitation can result in remote code execution. (As of 2020.1.114, a default setting prevents the exploit. In 2019.3.1023, but not earlier versions, a non-default setting can prevent exploitation.)

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Unchanged. Impact stays within the vulnerable component.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-502: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Affected products

• Telerik Ui For Asp.Net Ajax: from 2011.1.315 up to and including 2020.1.114

References

• https://www.telerik.com/support/kb/aspnet-ajax/details/allows-javascriptserializer-deserialization
• https://www.telerik.com/support/whats-new/release-history
• http://packetstormsecurity.com/files/155720/Telerik-UI-Remote-Code-Execution.html
• http://packetstormsecurity.com/files/159653/Telerik-UI-ASP.NET-AJAX-RadAsyncUpload-Deserialization.html
• https://github.com/bao7uo/RAU_crypto
• https://github.com/noperator/CVE-2019-18935
• https://know.bishopfox.com/research/cve-2019-18935-remote-code-execution-in-telerik-ui
• https://www.telerik.com/support/whats-new/aspnet-ajax/release-history/ui-for-asp-net-ajax-r1-2020-%28version-2020-1-114%29
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-18935
• https://codewhitesec.blogspot.com/2019/02/telerik-revisited.html
• https://www.bleepingcomputer.com/news/security/us-federal-agency-hacked-using-old-telerik-bug-to-steal-data/