YandexCloud SmartCaptcha Content-Security-Policy Bypass Scanner

YandexCloud SmartCaptcha is a service used widely for verifying user actions on web applications to prevent automated requests. It is predominantly utilized by businesses leveraging Yandex services to enhance user security and reduce spam submissions. The SmartCaptcha is integrated into various platforms to protect forms, logins, and sign-up pages from bot attacks, ensuring only genuine user interactions are processed. Developers and system integrators incorporate SmartCaptcha to streamline verification processes within Yandex's ecosystem. It serves not only security functions but also optimizes user experience by minimizing disruption during verification. Organizations across different sectors, with exposure to the digital sphere, employ SmartCaptcha to mitigate risks associated with automated attacks.

This scanner identifies a Cross-Site Scripting (XSS) vulnerability within the implementation of YandexCloud SmartCaptcha. XSS vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users, leading to possible hijacking of user sessions or redirection to malicious sites. The identified XSS vulnerability in YandexCloud SmartCaptcha occurs due to weaknesses in the Content-Security-Policy configuration that fails to adequately protect against script injection. Detection of this particular issue aids in mitigating extensive security risks associated with unauthorized script execution. It emphasizes ensuring robust CSPs are in place to handle interactive elements like captcha integrations effectively.

The assessment focuses on detecting how Content-Security-Policy bypass mechanisms could lead to XSS vulnerabilities in interfaces protected by YandexCloud SmartCaptcha. Specifically, it examines the capability of injecting scripts on the captcha-loaded interface, which, if successful, confirms a CSP bypass opportunity for XSS exploitation. The vulnerability checker performs HTTP GET requests and headless browser navigation to simulate user interactions and verifies CSP leakage points by injecting specific scripts. The presence of specified script indicators within the HTTP headers or interactive dialogs signals the vulnerability. Ensuring header contents strictly enforce CSPs can substantially reduce these risk exposures.

Exploiting such a vulnerability can have significant impacts on both users and systems. Attackers might execute harmful scripts that lead to unauthorized actions, data theft, or spread further malware. Legitimate user's sessions could be hijacked, leading to privacy breaches or exploitation of user privileges. Business reputations may suffer due to possible exposure of user data, leading to trust deficits and potential regulatory fines. Moreover, systems might become vectors for larger attacks, leveraging this vulnerability as an entry point. Addressing these vulnerabilities is crucial to hardening the security of services that rely on YandexCloud SmartCaptcha.

REFERENCES

• https://github.com/renniepak/CSPBypass/blob/main/data.tsv