Advisory: Open DHCP Server (V1.75/ V0.1 Beta) Privilege Escalation (CVE-2020-26131)
Summary
Product: Open DHCP Server
Affected versions:
- Open DHCP Server (Regular) - V1.75
- Open DHCP Server (LDAP Based) - V0.1Beta
Vendor: Achal Dhir
Fixed version: No response from vendor
Tested versions:
- Open DHCP Server (Regular) - V1.75
- Open DHCP Server (LDAP Based) - V0.1Beta
CVE Reference: CVE-2020-26131
CWE Reference: CWE-269
Problem Description
The folder permissions on the default installation directory %SYSTEMDRIVE%\OpenDHCPServer\ (Regular) or %SYSTEMDRIVE%\OpenDHCPLdap\ (LDAP Based) allows anyone in the "Authenticated Users" group to modify its contents. To exploit this vulnerability, a local attacker can replace the OpenDHCPServer.exe or the OpenDHCPLdap.exe with a crafted binary with the same name. Afterwards, if the service is restarted, the attacker's code will be executed in the context of system. The service gets automatically started after a reboot.
Impact
By replacing the binary an attacker can execute code, allowing potential privilege escalation to system.
Workaround
It is advised to change the installation directory to %SYSTEMDRIVE%\Program Files\ or %SYSTEMDRIVE%\Program Files(x86)\. By default, these directories allow "Authenticated Users" to only read and execute the directory contents.
Notes
The issue was reported to the vendor, but there was no response.
Disclosure Timeline
2020-07-28: Vulnerability discovered
2020-07-28: Vulnerability reported to vendor via Sourceforge
2020-09-29: CVE reserved
2020-10-26: 90-day disclosure deadline passed
2020-10-28: Published advisory
References
https://sourceforge.net/projects/dhcpserver/
Changes
2020-11-30: Corrected CWE
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