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CVE-2021-30116 - Unauthenticated credential leak and business logic flaw in Kaseya VSA <= v9.5.6

CVE CVE-2021-30116
Case DIVD-2021-00011
Discovered by
Products Kaseya:
  • Kaseya VSA (on premise)
Versions Kaseya:
  • Kaseya VSA (on premise)
    • 9.x (<= 9.5.6)
CVSS Base score: 10
Solution Upgrade to a version after 9.5.6
Last modified 20 Jun 2022 09:35


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.


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.

Screenshot of /dl.asp page

Image 1. Screenshot of

Screenshot of KaseyaD.ini file

Image 2. Screenshot of KaseyaD.ini file

Screenshot of obtaining a session cookie

Image 3. Screenshot of obtaining a session cookie

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