# CVE-2019-18935: Progress Telerik UI - RCE

> Live exploitation tracking for CVE-2019-18935 by the CrowdSec Live Exploit Tracker, built from real-world attack data crowdsourced from CrowdSec's global network.

Page: https://tracker.crowdsec.net/cves/CVE-2019-18935

## Key facts

- **Exploitation phase:** Background Noise. Continuous low-level scanning or exploitation attempts are observed, mostly opportunistic and automated.
- **CVSS score:** 9.8
- **Public exploit available:** Yes
- **Affected products:** Progress Telerik UI
- **Weaknesses:** CWE-502 (Deserialization of Untrusted Data)
- **Tags:** web_application

## 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.)

## CrowdSec analysis

[CVE-2019-18935](https://euvd.enisa.europa.eu/vulnerability/CVE-2019-18935) is a critical vulnerability in Progress Telerik UI for ASP.NET AJAX that enables remote code execution through a flawed deserialization process in the RadAsyncUpload functionality, especially when encryption keys are exposed or known.

CrowdSec has been tracking this vulnerability and its exploits since 5th of April 2023.

Based on data from the CrowdSec network, nearly all observed exploitation of CVE-2019-18935 is fully opportunistic, with attackers indiscriminately scanning the entire internet. These attacks are automated and lack any form of target selection or reconnaissance.
Additionally, according to week-over-week analysis by CrowdSec, exploitation of CVE-2019-18935 is surging. Attack volumes are spiking well above historical norms, indicating widespread and escalating interest from threat actors. CVE-2019-18935 is currently experiencing high visibility and active exploitation across the internet.

Observed exploitation frequently involves requests crafted to abuse the RadAsyncUpload feature, leveraging the underlying deserialization flaw for code execution.

## Timeline

- 2019-12-11: CVE Published. CVE-2019-18935 is published to NVD.
- 2021-11-03: CISA KEV. CVE-2019-18935 is added to the Known Exploited Vulnerabilities catalog by CISA.
- 2022-05-03: CISA Remediation Deadline. Expiration of the CISA remediation deadline as described in [BOD 22-01](https://www.cisa.gov/news-events/directives/bod-22-01-reducing-significant-risk-known-exploited-vulnerabilities).
- 2023-04-05: Rule Released. CrowdSec releases a rule to detect CVE-2019-18935 exploitation attempts against the CrowdSec Network.
- 2023-04-05: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2019-18935 for the first time.

## References

- https://www.telerik.com/support/whats-new/release-history
- https://codewhitesec.blogspot.com/2019/02/telerik-revisited.html
- https://github.com/bao7uo/RAU_crypto
- https://github.com/noperator/CVE-2019-18935
- https://www.telerik.com/support/whats-new/aspnet-ajax/release-history/ui-for-asp-net-ajax-r1-2020-%28version-2020-1-114%29

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2019-18935) follows observed exploitation activity for CVE-2019-18935. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.