CVE-2021-30116

CriticalActively exploited (CISA KEV)Known to be used in ransomware campaigns

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.

SeverityCritical
CVSS10.0
Exploit probability—
ProductKaseya Virtual System/Server Administrator (VSA)
PublishedJul 9, 2021
First seenJul 9, 2021
Added to KEVNov 3, 2021
Weakness typeCWE-522CWE-522

How to fix

CISA required action

Apply updates per vendor instructions.

CISA due date: Nov 17, 2021
Update
  • kaseya vsa_agent9.5.0.24 or later
  • kaseya vsa_server9.5.7a or later

Affected products

ProductAffected versionsFixed in
kaseya vsa_agentv < 9.5.0.249.5.0.24
kaseya vsa_serverv < 9.5.7a9.5.7a

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