CVE-2021-30116

10.0 CRITICAL CISA KEV - Actively Exploited
Published: July 09, 2021 Modified: November 10, 2025

Description

Kaseya VSA before 9.5.7 allows credential disclosure, as exploited in the wild in July 2021. By default Kaseya VSA on premise offers a download page where the clients for the installation can be downloaded. The default URL for this page is https://x.x.x.x/dl.asp When an attacker download a client for Windows and installs it, the file KaseyaD.ini is generated (C:\Program Files (x86)\Kaseya\XXXXXXXXXX\KaseyaD.ini) which contains an Agent_Guid and AgentPassword This Agent_Guid and AgentPassword can be used to log in on dl.asp (https://x.x.x.x/dl.asp?un=840997037507813&pw=113cc622839a4077a84837485ced6b93e440bf66d44057713cb2f95e503a06d9) This request authenticates the client and returns a sessionId cookie that can be used in subsequent attacks to bypass authentication. Security issues discovered --- * Unauthenticated download page leaks credentials * Credentials of agent software can be used to obtain a sessionId (cookie) that can be used for services not intended for use by agents * dl.asp accepts credentials via a GET request * Access to KaseyaD.ini gives an attacker access to sufficient information to penetrate the Kaseya installation and its clients. Impact --- Via the page /dl.asp enough information can be obtained to give an attacker a sessionId that can be used to execute further (semi-authenticated) attacks against the system.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/
Source: cve@mitre.org
Third Party Advisory
https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/
Source: cve@mitre.org
Third Party Advisory
https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/
Source: cve@mitre.org
Exploit Third Party Advisory
https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

9 reference(s) from NVD

Quick Stats

CVSS v3 Score
10.0 / 10.0
EPSS (Exploit Probability)
49.8%
98th percentile
Exploitation Status
Actively Exploited
Remediation due: 2021-11-17

Weaknesses (CWE)

Affected Vendors

kaseya