Security Experts:

Cisco Says Hackers Targeting Zero-Days in Carrier-Grade Routers

Cisco has warned that hackers are targeting not one, but two unpatched vulnerabilities in the DVMRP feature of IOS XR software that runs on many carrier-grade routers. 

Over the weekend, the company published an advisory to warn of active attacks targeting a security flaw (CVE-2020-3566) in the Distance Vector Multicast Routing Protocol (DVMRP) feature of IOS XR to cause memory exhaustion denial of service (DoS). 

On Monday, the tech giant has updated the advisory to add another CVE to it, namely CVE-2020-3569, which impacts the very same feature and has similar consequences. 

Both issues, the company reveals, can be exploited remotely, by an unauthenticated attacker, by sending crafted IGMP traffic to a vulnerable device. 

The bugs exist because there is insufficient queue management for Internet Group Management Protocol (IGMP) packets.

According to the company, all Cisco devices that are running any release of IOS XR software are affected, provided that an active interface is configured under multicast routing. Impacted devices include: ASR 9000, NCS 5500, 8000, as well as NCS 540 & 560 series routers.

Cisco has shared information on mitigation steps organizations can take to limit exposure, but has yet to release software updates to address these vulnerabilities. 

No workarounds to address the two issues have been detailed yet, but Cisco has published indicators of compromise to help administrators determine whether attackers are exploiting the vulnerabilities in their devices.

Related: Attackers Actively Targeting Cisco IOS XR Vulnerability

Related: Cisco Patches High-Severity Vulnerabilities in NX-OS Software

Related: Default Credentials Expose Cisco ENCS, CSP Appliances to Attacks

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