

In November 2022, our bug bounty program received a critical and very interesting report. The report stated that certain types of DNS records could be used to bypass some of our network policies and connect to ports on the loopback address (e.g. 127.0.0.1) of our servers. This post will explain how we dealt with the report, how we fixed the bug, and the outcome of our internal investigation to see if the vulnerability had been previously exploited.
RFC 4291 defines ways to embed an IPv4 address into IPv6 addresses. One of the methods defined in the RFC is to use IPv4-mapped IPv6 addresses, that have the following format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
In IPv6 notation, the corresponding mapping for 127.0.0.1 is ::ffff:127.0.0.1 (RFC 4038)
The researcher was able to use DNS entries based on mapped addresses to bypass some of our controls and access ports on the loopback address or non-routable IPs.
This vulnerability was reported on November 27 to our bug bounty program. Our Security Incident Response Team (SIRT) was contacted, and incident response activities Continue reading
The simplest way to implement layer-3 forwarding in a network fabric is to offload it to an external device1, be it a WAN edge router, a firewall, a load balancer, or any other network appliance.

Routing at the (outer) edge of the fabric
The simplest way to implement layer-3 forwarding in a network fabric is to offload it to an external device1, be it a WAN edge router, a firewall, a load balancer, or any other network appliance.

Routing at the (outer) edge of the fabric


Over the past few days, Cloudflare, as well as other sources, have observed healthcare organizations targeted by a pro-Russian hacktivist group claiming to be Killnet. There has been an increase in the amount of healthcare organizations coming to us to help get out from under these types of attacks. Multiple healthcare organizations behind Cloudflare have also been targeted by HTTP DDoS attacks and Cloudflare has helped them successfully mitigate these attacks. The United States Department of Health and Human Services issued an Analyst Note detailing the threat of Killnet-related cyberattacks to the healthcare industry.
A rise in political tensions and escalation of the conflict in Ukraine are all factors that play into the current cybersecurity threat landscape. Unlike traditional warfare, the Internet has enabled and empowered groups of individuals to carry out targeted attacks regardless of their location or involvement. Distributed-denial-of-Service (DDoS) attacks have the unfortunate advantage of not requiring an intrusion or a foothold to be launched and have, unfortunately, become more accessible than ever before.
The attacks observed by the Cloudflare global network do not show a clear indication that they are originating from a single botnet and the attack methods and sources Continue reading
https://codingpackets.com/blog/aws-networking
https://codingpackets.com/blog/cloud-notes-aws-vpc
https://codingpackets.com/blog/aws-networking
https://codingpackets.com/blog/cloud-notes-aws-vpc
https://codingpackets.com/blog/cloud-notes-aws-vpc
https://codingpackets.com/blog/cloud-notes-aws-vpc
https://codingpackets.com/blog/cloud-notes-aws-vpc
https://codingpackets.com/blog/aws-networking