PSIRT Advisories

FortiClient installer DLL Hijacking Vulnerability

Summary

Multiple unsafe search path vulnerabilities in FortiClient online installers may allow an attacker with control over the directory in which the installers reside to execute arbitrary code on the system via uploading malicious .dll files in that directory.

Affected Products

FortiClientOnlineInstaller.exe for FortiClient for Windows 6.0.5 and below (CVE-2019-5589)
FortiClientOnlineInstaller.exe for FortiClient for Windows 6.4.6 and below, and 7.0.0 (CVE-2020-9290)
FortiClientVPNOnlineInstaller.exe for FortiClient VPN for Windows 6.4.6 and below, and 7.0.0 (CVE-2020-9290)
FortiClientEMSOnlineInstaller.exe for FortiClient EMS 6.2.8 and below, 6.4.6 and below and 7.0.0 (CVE-2020-9287)

Solutions

CVE-2019-5589: Use FortiClient for Windows online installer 6.0.6 or above
CVE-2020-9290: Use FortiClient for Windows online installer 6.4.7 or above, 7.0.1 or above, and FortiClient VPN for Windows online installer 6.4.7 or above, 7.0.1 or above
CVE-2020-9287: Use FortiClient EMS online installer 6.2.9 or above, 6.4.7 or above, 7.0.1 or above.
Revision History:
05-16-2019 Initial version
3-09-2020 add CVE-2020-9290 and CVE-2020-9287
13-9-2021 modified CVE-2020-9290
8-11-2021 add CVE-2020-9290 and CVE-2020-9287

Acknowledgement

Fortinet is pleased to thank Independent security researcher Honc (honcbb@gmail.com)for reporting CVE-2019-5589 and CVE-2020-9290, Houjingyi (houjingyi647@gmail.com) for reporting CVE-2020-9290 and CVE-2020-9287, security researcher Eran Shimony from CyberArk Labs for reporting CVE-2020-9290 and independent researcher AmeenBasha M K for reporting CVE-2020-9290 under responsible disclosures.