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Multiple Vulnerabilities in Kaseya VSA Could Allow for Arbitrary Code Execution

MS-ISAC ADVISORY NUMBER:

2021-085

DATE(S) ISSUED:

07/12/2021

OVERVIEW:

Multiple vulnerabilities have been discovered in Kaseya VSA that could allow for arbitrary code execution. Kaseya VSA is a software used by MSPs to remotely manage networks and endpoints. Successful exploitation of these vulnerabilities could result in arbitrary code execution within the context of the application, an attacker gaining the same privileges as the logged-on user, or the bypassing of security restrictions. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

THREAT INTELLIGENCE:

It is reported that at least 50 direct Kaseya customers were impacted leading to between 800 to 1500 downstream businesses being exploited with these vulnerabilities.

SYSTEMS AFFECTED:

  • Kaseya VSA On-premises versions prior to 9.5.7a (9.5.7.2994)

RISK:

Government:
  • Large and medium government entities: HIGH
  • Small government entities: MEDIUM
Businesses:
  • Large and medium business entities: HIGH
  • Small business entities: MEDIUM
Home Users: LOW

TECHNICAL SUMMARY:

Multiple vulnerabilities have been discovered in Kaseya VSA that could allow for arbitrary code execution. These vulnerabilities can be exploited remotely if an attacker locates a vulnerable Kaseya Web interface. An attacker can exploit this issue to execute arbitrary code in the context of the running Kaseya server process. Details of these vulnerabilities are as follows:  
Credentials leak and business logic flaw - CVE-2021-30116
XSS vulnerability - CVE-2021-30119
2FA bypass - CVE-2021-30120

Network IOCs

35.226.94[.]113
161.35.239[.]148
162.253.124[.]162

Endpoint IOCs

 
Filename MD5 Hash Function
cert.exe N/A - File with random string appended Legit certutil.exe Utility
agent.crt 939aae3cc456de8964cb182c75a5f8cc Encoded malicious content
agent.exe 561cffbaba71a6e8cc1cdceda990ead4 Decoded contents of agent.crt
mpsvc.dll a47cf00aedf769d60d58bfe00c0b5421 Ransomware Payload

Web Log Indicators

POST /dl.asp curl/7.69.1
GET /done.asp curl/7.69.1
POST /cgi-bin/KUpload.dll curl/7.69.1
GET /done.asp curl/7.69.1
POST /cgi-bin/KUpload.dll curl/7.69.1
POST /userFilterTableRpt.asp curl/7.69.1

Successful exploitation of these vulnerabilities could result in arbitrary code execution within the context of the application, an attacker gaining the same privileges as the logged-on user, or the bypassing of security restrictions. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

RECOMMENDATIONS:

We recommend the following actions be taken:
  • Apply appropriate updates and recommendations provided by Kaseya to vulnerable systems immediately after appropriate testing.
  • Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources.
  • Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources.
  • Apply the Principle of Least Privilege to all systems and services.

REFERENCES:

Kaseya: https://www.kaseya.com/potential-attack-on-kaseya-vsa/ https://helpdesk.kaseya.com/hc/en-gb/articles/4403785889041 https://helpdesk.kaseya.com/hc/en-gb/articles/4403760102417   ZDNet: https://www.zdnet.com/article/kaseya-ransomware-updates-attack-your-questions-answered/   CVE: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30116 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30119 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30120

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