CVE-2021-30116
Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 85.73% probability · 100th percentile
- CISA KEV
- Listed 3 November 2021 · due 17 November 2021 · used in ransomware campaigns
- Weakness
- CWE-522
- Affected
- kaseya/vsa agent · kaseya/vsa server
- Source
- cve@mitre.org
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-30116
References
- https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/Third Party Advisory
- https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/Third Party Advisory
- https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021Vendor Advisory
- https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/Exploit, Third Party Advisory
- https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/Third Party Advisory
- https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/Third Party Advisory
- https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021Vendor Advisory
- https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/Exploit, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.