CVEvulnerability

CVE-2021-30116

9.8 CRITICAL Known exploited Published 2021-07-09 Modified 2026-08-14 Official page ↗

CISA Known Exploited Vulnerability

Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability — Kaseya Virtual System/Server Administrator (VSA)

Kaseya Virtual System/Server Administrator (VSA) contains an information disclosure vulnerability allowing an attacker to obtain the sessionId that can be used to execute further attacks against the system.

Added to KEV: 2021-11-03
Remediation due: 2021-11-17
Ransomware use: Known
Required action: Apply updates per vendor instructions.
Notes: https://nvd.nist.gov/vuln/detail/CVE-2021-30116

Status: Analyzed
Published: 2021-07-09
Last modified: 2026-08-14
Assigner: [email protected]
CVSS 3.1 ([email protected]): 10.0 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS 3.1 ([email protected]): 9.8 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0 ([email protected]): 7.5 HIGH — AV:N/AC:L/Au:N/C:P/I:P/A:P
Weaknesses: CWE-522

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.

Affected configurations

• kaseya vsa agent (< 9.5.0.24) • kaseya vsa server (< 9.5.7a)

Weakness · CWE (1)

CWE-522 Insufficiently Protected Credentials weakness

References