CVE-2021-30121:Semi-authenticated local file inclusion vulnerability in Kaseya VSA allows attackers to read arbitrary files from the server.

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CVE-2021-30121 is a semi-authenticated local file inclusion vulnerability affecting Kaseya VSA. This vulnerability allows attackers to read the contents of arbitrary files on the server by manipulating the path parameter in requests to the js.aspx endpoint. While authentication is required, valid session IDs can be easily obtained by exploiting another vulnerability, CVE-2021-30118. This vulnerability was part of a series of issues discovered in Kaseya VSA that were exploited in significant supply chain attacks.

Overview

The vulnerability exists in the js.aspx file within the Kaseya VSA application. By manipulating the "path" parameter, an attacker can access files outside the intended directory structure. For example, an attacker could send a request like: "https://x.x.x.x/KLC/js/Kaseya.SB.JS/js.aspx?path=C:\Kaseya\WebPages\dl.asp" to read the contents of the dl.asp file. While the vulnerability requires a valid sessionId for exploitation, attackers can easily obtain one by leveraging CVE-2021-30118, making this vulnerability particularly dangerous. This type of vulnerability is classified as CWE-829 (Inclusion of Functionality from Untrusted Control Sphere).

Remediation

Organizations using Kaseya VSA should immediately apply the security patches provided by Kaseya that address this vulnerability. In addition, the following measures are recommended:

  1. Update to the latest version of Kaseya VSA that contains the security fix
  2. Implement proper input validation to prevent path traversal attacks
  3. Apply the principle of least privilege to service accounts
  4. Monitor system logs for suspicious file access attempts
  5. Consider implementing web application firewalls to detect and block path traversal attempts
  6. Ensure that all related vulnerabilities, especially CVE-2021-30118, are also patched

References

  1. DIVD Limited Disclosure: https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/
  2. DIVD Vulnerability Details: https://csirt.divd.nl/CVE-2021-30121
  3. DIVD Case Report: https://csirt.divd.nl/DIVD-2021-00011
  4. Related vulnerability: CVE-2021-30118 (which can be used to obtain session IDs)

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Accommodation & Food Services
    Accommodation & Food Services
  2. Administrative, Support, Waste Management & Remediation Services
    Administrative, Support, Waste Management & Remediation Services
  3. Agriculture, Forestry Fishing & Hunting
    Agriculture, Forestry Fishing & Hunting
  4. Arts, Entertainment & Recreation
    Arts, Entertainment & Recreation
  5. Construction
    Construction
  6. Educational Services
    Educational Services
  7. Finance and Insurance
    Finance and Insurance
  8. Health Care & Social Assistance
    Health Care & Social Assistance
  9. Information
    Information
  10. Management of Companies & Enterprises
    Management of Companies & Enterprises
  11. Manufacturing
    Manufacturing
  12. Mining
    Mining
  13. Other Services (except Public Administration)
    Other Services (except Public Administration)
  14. Professional, Scientific, & Technical Services
    Professional, Scientific, & Technical Services
  15. Public Administration
    Public Administration
  16. Real Estate Rental & Leasing
    Real Estate Rental & Leasing
  17. Retail Trade
    Retail Trade
  18. Transportation & Warehousing
    Transportation & Warehousing
  19. Utilities
    Utilities
  20. Wholesale Trade
    Wholesale Trade

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  2. Identify True Risk.
  3. Proactively Mitigate Threats.

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Armis Vulnerability Intelligence Database