Authentication bypass in Systemd DHCP client

1) Predictable from Observable State

EUVDB-ID: #VU52596

Risk: Low

CVSSv4.0: 1.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-13529

CWE-ID: CWE-341 - Predictable from Observable State

Exploit availability: No

Description

The vulnerability allows a remote attacker to reconfigure the target device.

The vulnerability exists due to usage of predictable Transactions Identifiers when processing DHCP ACK packets. A remote attacker on the same network can forge the FORCERENEW and DHCP ACK packets to reconfigure the systemd’s DHCP client settings.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

systemd: 216 - 247.6

CPE2.3

• cpe:2.3:a:freedesktop_org:systemd:216:*:*:*:*:*:*:*
• cpe:2.3:a:freedesktop_org:systemd:217:*:*:*:*:*:*:*
• cpe:2.3:a:freedesktop_org:systemd:218:*:*:*:*:*:*:*

External links

https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1142

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.