This is a personal blog of 0xCardinal. I write about Information Security, Learnings, CTF WriteUps, etc.

My Experiments with Raspberry Pi Pico - Poor Man's Rubber Ducky
Mr. Robot Season 2 Episode 9 - “Rubber Duckie, You’re The One” - I was fascinated by this piece of technology when I first saw it many years ago. Then I looked it up on the internet to learn more about it, and it turned out to be HID, or Human Interface Device. It basically imitates users and executes code or performs actions in their place. Since the real rubber ducky was out of my budget, I looked for alternatives and discovered that similar behaviour to the rubber ducky can be achieved using a less expensive piece of hardware - the Raspberry Pi Pico (7$)....

Docker Security
Last Updated on 2nd Feb 2023. Containers? Why do we need containers over VMs - Efficient Resource Consumption between containers Once License for services/OS Low Compute Overhead What does docker engine does? Emulates Filesystem Gives each container unique process ID Isolation of container process Communication between the architecture components - Components Docker client (The one user interacts with) Docker Host Docker Daemon Images Containers Registry Docker client using serveral API calls sends the commands to Docker Engine which is being forwarded to containerd....

Zone Identifier - Is your file downloaded from the internet?
Have you ever wondered, why your file is not working after downloading it from the internet? How does system know if the file is downloaded from the internet? The answers to this is Zone.Identifiers. What are Zone Identifiers? Zone Identifiers is an alternate data stream that points, from where the file came on the users' computer. Note: Alternate Data Streams are included with files on WIndows. This is typically the case with downloaded and blocked files....

Understanding DKIM - Email Security Series
DKIM is a technological advancement in the field of email security. SPF prevents non-authorized servers from sending emails, but it does not prevent all attempts at spoofing. This is where our next level of security comes into play. DKIM or Domain Keys Identified Mail aids to the security of the email as it adds a digital signature to every outgoing message, allowing receiving servers to verify that the message came from your organization....

Understanding SPF - Email Security Series
Sender Policy Framework or SPF is an email authentication platform. It helps in specifying who is allowed to send emails from your domain. Making it harder for fraudsters to spoof sender information. RFC 7208 - https://datatracker.ietf.org/doc/html/rfc7208 SPF Records are used to specify the origin of the email to the world. It can be considered as a public list that specifies where an email is sent from. How does SPF records look like?...

Linux - Command Line Struggles
Configure Network Using ip Command in Ubuntu Server Temporary Method - $ ip a # to get the interface name after connecting LAN $ sudo ip a add 192.168.1.8/24 dev <network-interface-name> $ ip link set dev <network-interface-name> up $ sudo ip route add default via 192.168.1.1 Permanent Solution - Ref: https://netplan.io/examples/ $ vim /etc/netplan/00-installer-config.yaml network: version: 2 ethernets: enx1027f579a565: dhcp4: false addresses: [192.168.1.10/24] nameservers: addresses: [8.8.8.8,8.8.4.4,192.168.1.1] routes: - to: default via: 192....

gRPC: We are not RESTing Anymore
gRPC is a framework which is being used to build scalable and fast APIs. The framework from which it derives most of its positives is from the protocol it uses - HTTP/2. Apart from HTTP/2, it uses protocol buffer (protobuf) for the communication. gRPC can be useful in circumstances like - large-scale microservices connections real-time communication Low power & low bandwidth systems Multi-language environments Why Should We Care? Let’s talk Benefits The use of HTTP/2 over the TLS end-to-end encryption connection in gRPC ensures API security....

How is XSS different from CSRF?
An interesting discussion, led me to realize this is one of the commonly discussed topic and I thought a blog post for it might be helpful for someone. Cross-site request forgery and Cross-site scripting are both client side attacks which performs action on behalf of users. Just some context here - Cross-site scripting (or XSS) allows an attacker to execute arbitrary JavaScript within the browser of a victim user....