Zyxel security advisory for DNSpooq

Zyxel security advisory for DNSpooq 

CVE: CVE-2020-25681, CVE-2020-25682, CVE-2020-25683, CVE-2020-25684, CVE-2020-25685, 

　　  CVE-2020-25686, CVE-2020-25687

Summary

Zyxel will release patches for products affected by the Dnsmasq vulnerabilities reported by CERT/CC. Users are advised to install the applicable firmware updates or follow the best practices for optimal protection.

What is the vulnerability?

Dnsmasq, open-source software that provides DNS forwarding and caching, has two sets of vulnerabilities, as listed below. Dubbed as DNSpooq, these vulnerabilities could allow an attacker to corrupt memory on the target device and perform cache poisoning attacks against the target environment.

• Memory corruption vulnerabilities due to boundary checking errors in DNSSEC handling code.

　　　　(CVE-2020-25681, CVE-2020-25682, CVE-2020-25683, and CVE-2020-25687)

• DNS response validation vulnerabilities that can result in DNS cache poisoning.

　　　　(CVE-2020-25684, CVE-2020-25685, and CVE-2020-25686)

What versions are vulnerable—and what should you do?

After a thorough investigation, we’ve identified products that make use of the Dnsmasq software and confirmed that these products are only affected by the DNS response validation vulnerabilities with medium severity. We’ll include the solution in the affected products’ next regular firmware releases to address the issues, as shown in the table below. For optimal protection, we urge users to install the applicable updates when they become available or follow CERT/CC’s best practices when protecting DNS infrastructure before the firmware updates become available:

• Protect your DNS clients and DNS client software using stateful-inspection firewall that can provide application security.

• Provide secure DNS recursion service with features such as DNSSEC validation and the interim 0x20-bit encoding as part of enterprise DNS services where applicable.

• Prevent exposure of IoT devices and lightweight devices directly over the Internet to minimize abuse of DNS.

• Regularly update software and embedded firmware to the latest available version and the recommended secure configuration suitable for your operations environment (e.g., disable caching if not needed or provided by an upstream server).

Please note that the table does NOT include customized models for internet service providers (ISPs). For ISP customers, please contact your Zyxel representative for further details. For end-users, please contact your local Zyxel support team or visit our forum if you require further assistance.

Affected series/models	Patch available in
CPE
AX7501-B0	V5.15(ABPC.1)C0 in June 2021
DX5510-B0	V5.17(ABVV.1)C0 in Dec 2021
EMG3525-T50B	V5.50(ABPM.6)C0 in June 2021
EMG5523-T50B	V5.50(ABPM.6)C0 in June 2021
EMG5723-T50K	V5.50(ABOM.7)C0 in June 2021
EMG6726-B10A	V5.13(ABNP.7)C0 in Dec 2021
EX3510-B0	V5.17(ABUP.4)C0 in Dec 2021
EX5501-B0	V5.15(ABRY.2)C0 in June 2021
EX5510-B0	V5.17(ABQX.4)C0 in Dec 2021
VMG1312-T20B	V5.50(ABSB.5)C0 in June 2021
VMG3625-T50B	V5.50(ABPM.6)C0 in June 2021
VMG3927-B50A_B60A	V5.15(ABMT.7)C0 in June 2021
VMG3927-B50B	V5.13(ABLY.7)C0 in Dec 2021
VMG3927-T50K	V5.50(ABOM.7)C0 in June 2021
VMG4005-B50B	V5.13(ABRL.5)C0 in Dec 2021
VMG4927-B50A	V5.13(ABLY.7)C0 in Dec 2021
VMG8623-T50B	V5.50(ABPM.6)C0 in June 2021
VMG8825-B50A_B60A	V5.15(ABMT.7)C0 in June 2021
VMG8825-Bx0B	V5.15(ABNY.7)C0 in June 2021
VMG8825-T50K	V5.50(ABOM.7)C0 in June 2021
XMG3927-B50A	V5.15(ABMT.7)C0 in June 2021
XMG8825-B50A	V5.15(ABMT.7)C0 in June 2021
ONT
PMG2005-T20D	V1.00(ABWX.1)C0 in Q2 2021
PMG5317-T20B	V5.40(ABKI.4)C0 in Q2 2021
PMG5617GA	V5.40(ABNA.2)C0 in Q2 2021
PMG5622GA	V5.40(ABNB.2)C0 in Q2 2021
LTE
LTE1566	V1.00(ABUD.3)C0*
LTE2566	V1.00(ABTW.3)C0*
LTE3202	V1.00(ABVM.3)C0*
LTE3301	V1.00(ABLG.5)C0*
LTE3301Plus	V1.00(ABQU4)C0 in Q2 2021
LTE3302	V1.00(ABLM.5)C0*
LTE3316	V1.00(ABMP.5)C0*
LTE5366	V1.00(ABKA.2)C0*
LTE7460	V1.00(ABFR.6)C0*
LTE7461	V2.00(ABQN.3)C0 in Q2 2021
LTE7480	V1.00(ABRA.3)C0 in Q2 2021
LTE7485	V1.00(ABVN.3)C0 in Q2 2021
LTE7490	V1.00(ABQY.1)C0 in Q2 2021
WAH7601	V1.00(ABRH.3)C0*
WAH7608	V1.00(ABKW.2)C0*
WAH7706	V1.00(ABBC.12)C0*
Home router
NBG418v2	V1.00(AARP.10)C0 in Dec 2021
NBG6515	V1.00(AAXS.8)C0 in Dec 2021
NBG6604	V1.00(ABIR.6)C0 in Dec 2021
NBG6615	V1.00(ABMV.5)C0 in Dec 2021
NBG6817	V1.00(ABCS.11)C0 in Sep 2021
NBG6818	V1.00(ABSC.5)C0 in Sep 2021
NBG7815	V1.00(ABSK.6)C0 in Sep 2021
WSQ50	V2.20(ABKJ.5)C0 in Sep 2021
WSQ60	V2.20(ABND.6)C0 in Sep 2021
WSR30	V1.00(ABMY.12)C0 in Sep 2021
AP and AP controller
Unified Pro series	V6.20 in Mar 2021
Unified series	V6.20 in Mar 2021
Standalone series	V6.20 in Mar 2021
Cloud-managed series	V6.20 in Mar 2021
NXC2500/5500	V6.20 in Mar 2021
Firewall
VPN2S	Hotfix available upon request*

*Please reach out to your local Zyxel support team for the file.

Got a question or a tipoff?

Please contact your local service rep for further information or assistance. If you’ve found a vulnerability, we want to work with you to fix it—contact security@zyxel.com.tw and we’ll get right back to you.

Acknowledgment

Thanks to CERT/CC for reporting the issue to us.

Revision history

2021-1-21: Initial release