Widespread Exploitation of Zyxel Network Devices

-



Rapid7 is tracking reports of ongoing exploitation of CVE-2023-28771, a critical unauthenticated command injection vulnerability affecting multiple Zyxel networking devices.

The vulnerability is present in the default configuration of vulnerable devices and is exploitable in the Wide Area Network (WAN) interface, which is intended to be exposed to the internet. A VPN does not need to be configured on a device for it to be vulnerable. Successful exploitation of CVE-2023-28771 allows an unauthenticated attacker to execute code remotely on the target system by sending a specially crafted IKEv2 packet to UDP port 500 on the device.

Zyxel released an advisory for CVE-2023-28771 on April 25, 2023. On May 19, Rapid7 researchers published a technical analysis of the vulnerability on AttackerKB, underscoring the likelihood of exploitation.

As of May 19, there were at least 42,000 instances of Zyxel devices on the public internet. However, as Rapid7 researchers noted, this number only includes devices that expose their web interfaces on the WAN, which is not a default setting. Since the vulnerability is in the VPN service, which is enabled by default on the WAN, we expect the actual number of exposed and vulnerable devices to be much higher.

As of May 26, the vulnerability is being widely exploited, and compromised Zyxel devices are being leveraged to conduct downstream attacks as part of a Mirai-based botnet. Mirai botnets are frequently used to conduct DDoS attacks.

While CVE-2023-28771 is currently garnering large-scale threat actor attention, Zyxel published an advisory for two additional vulnerabilities — CVE-2023-33009 and CVE-2023-33010 — on May 24, 2023. CVE-2023-33009 and CVE-2023-33010 are buffer overflow vulnerabilities that can allow unauthenticated attackers to cause a DoS condition or execute arbitrary code on affected devices.

We strongly recommend that users of the affected Zyxel products update to the latest firmware on an emergency basis. At time of writing, the latest firmware version is 5.36 Patch 2, or 4.73 Patch 2 for ZyWALL/USG. See Zyxel’s advisory for additional details.

Rapid7 Customers

For InsightVM and Nexpose customers, a remote vulnerability check for CVE-2023-28771 has been available since the May 19, 2023 content release. Additional remote vulnerability checks for CVE-2023-33009 and CVE-2023-33010 are available in the May 31, 2023 content release.

Update May 31 12:45 PM ET: The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has now added CVE-2023-28771 to the Known Exploited Vulnerabilities (KEV) list.

E.K

Comments

Post a Comment

Popular posts from this blog

CISA and ENISA enhance their Cooperation

-
Image
  The European Union Agency for Cybersecurity (ENISA) has signed a Working Arrangement with the Cybersecurity and Infrastructure Security Agency (CISA) of the US, in the areas of capacity-building, best practices exchange and boosting situational awareness. Geopolitics have shaped the cyber threat landscape, bringing like-minded partners closer together in the wake of common cyber challenges and advances in digital technologies. Today at the EU-US Cyber Dialogue, ENISA and CISA announced the signing of their Working Arrangement as an important milestone in the overall cooperation between the United States and the European Union in the field of cybersecurity, also following the Joint Statement of European Commissioner Thierry Breton and U.S. Secretary for Homeland Security Alejandro Mayorkas of January 2023. ENISA’s International Strategy directs the Agency to be selective in engaging with international partners and to limit its overall approach in international cooperation to those...
Read more

Top Five Most Exploited Vulnerabilities in January 2024

-
Image
In January 2024, cybersecurity faced a remarkable surge in threats, with a focus on exploiting vulnerabilities in technologies from leading vendors. This spike in cyber attacks highlighted the urgent necessity for robust security posture and swift responses to mitigate these vulnerabilities.  Below is an in-depth analysis of the most critical vulnerabilities targeted during January. CVE-2023-46805 and CVE-2024-21887:   CISA Warns Against Ivanti Zero-Day Vulnerabilities On January 19, 2024, the Cybersecurity and Infrastructure Security Agency (CISA) issued an alert regarding two critical zero-day vulnerabilities discovered in Ivanti products:  CVE-2023-46805 and  CVE-2024-21887.  Assigned CVSS scores of 8.2 (High) and 9.1 (Critical), these vulnerabilities underscore a significant risk to cybersecurity, marked by their capability for arbitrary command execution. This prompted an emergency directive for immediate mitigation within federal agencies, highlighting the...
Read more

SmartScreen Vulnerability: CVE-2024-21412 Facts and Fixes

-
Image
On Feb. 13, 2024, Microsoft issued a  patch  for CVE-2024-21412, a  Microsoft Defender SmartScreen  vulnerability revolving around internet shortcuts. Previously, we discovered that an advanced persistent threat (APT) group we track under the name Water Hydra has been exploiting CVE-2024-21412 in a sophisticated campaign targeting financial market traders, allowing the group to bypass Microsoft Defender SmartScreen and infect its victims with the DarkMe remote access trojan (RAT). Threat actors are constantly finding new ways of identifying and exploiting gaps to bypass security measures. We found that the bypass of CVE-2023-36025 (a previously patched SmartScreen vulnerability) led to the discovery and exploitation of CVE-2024-21412. This highlights how threat actors can circumvent patches by identifying new vectors of attack around a patched software component. It is important that organizations are able to identify and mitigate vulnerabilities, especiall...
Read more