Improper Privilege Management in SpamTitan - CVE-2020-24046

Description

The vulnerability allows a remote administrator to escalate privileges.

The vulnerability exists due to improper privilege management. This restricted shell can be bypassed after changing the properties of the user admin in the operating system file /etc/passwd. This file cannot be accessed though the restricted shell, but it can be modified by abusing the Backup/Import Backup functionality of the web interface. An authenticated attacker would be able to obtain the file /var/tmp/admin.passwd after executing a Backup operation. This file can be manually modified to change the GUID of the user to 0 (root) and change the restricted shell to a normal shell /bin/sh. After the modification is done, the file can be recompressed to a .tar.bz file and imported again via the Import Backup functionality. The properties of the admin user will be overwritten and a root shell will be granted to the user upon the next successful login.

Remediation

External links

• https://github.com/felmoltor
• https://sensepost.com/blog/2020/clash-of-the-spamtitan/
• https://twitter.com/felmoltor
• https://www.titanhq.com