Improper access control in Cisco Access Points

1) Improper access control

EUVDB-ID: #VU67766

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-2021-27854

CWE-ID: CWE-284 - Improper Access Control

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions in the Layer 2 network filtering capabilities such as IPv6 RA guard. A remote attacker on the local network can bypass these capabilities using a combination of VLAN 0 headers, LLC/SNAP headers in Ethernet to Wifi frame translation and in the reverse-Wifi to Ethernet.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

6300 Series Embedded Services Access Points: All versions

Cisco Aironet 1540 Series Access Points: All versions

Aironet 1560 Series Access Points: All versions

Aironet 1800 Series Access Points: All versions

Aironet 2800 Series Access Points: All versions

Aironet 3800 Series Access Points: All versions

Aironet 4800 Access Points: All versions

Business 100 Series Access Points: All versions

Business 200 Series Access Points: All versions

Catalyst 9100 Access Points: All versions

Catalyst IW 6300 Heavy Duty Series Access Points: All versions

Integrated AP on 1100 Integrated Services Routers: All versions

Wireless LAN Controller Software: - - 8.10

Catalyst 9800 Wireless Controller Software: - - 17.6.2

CPE2.3

• cpe:2.3:a:cisco_systems:6300_series_embedded_services_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:cisco_aironet_1540_series:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:aironet_1560_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:aironet_1800_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:aironet_2800_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:aironet_3800_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:a:cisco_systems:aironet_4800_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:a:cisco_systems:business_100_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:a:cisco_systems:business_200_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:catalyst_9100_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:catalyst_iw_6300_heavy_duty_series_access_points:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:integrated_ap_on_1100_integrated_services_routers:*:*:*:*:*:*:*:*
• cpe:2.3:a:cisco_systems:wireless_lan_controller_software:*:*:*:*:*:*:*:*
• cpe:2.3:h:cisco_systems:catalyst_9800_wireless_controller_software:*:*:*:*:*:*:*:*

External links

https://blog.champtar.fr/VLAN0_LLC_SNAP/

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.