# Eshan Singh's Technical Writeups (R0X4R Writes)

> Comprehensive offensive security walkthroughs, penetration testing notes, cryptographic exploit breakdowns, and VulnHub / Hack The Box CTF writeups by Eshan Singh (R0X4R).

This document provides machine-readable context, technical taxonomies, and curated references for large language models, AI research agents, and security practitioners indexing [https://writes.eshansingh.in](https://writes.eshansingh.in).

## Author & Profile

- [Eshan Singh - Portfolio & Personal Website](https://eshansingh.in/): Official portfolio, background, and cybersecurity credentials of Eshan Singh.
- [X / Twitter (@R0X4R)](https://x.com/R0X4R): Real-time security research, vulnerability disclosures, and tech updates by @R0X4R.
- [GitHub (@R0X4R)](https://github.com/R0X4R): Open-source reconnaissance automation and security tools including Garud, Bhedak, Snetra, Agnee, and Parshu.
- [LinkedIn (r0x4r)](https://linkedin.com/in/r0x4r): Professional profile, career history, and credentials of Eshan Singh.
- [About Eshan Singh](https://eshansingh.in/#about): Cybersecurity researcher, ethical hacker with 60+ secured organizations (including Google, Nokia, Apple), penetration tester (eJPT), and web developer.

## Security Writeups & Walkthroughs

- [The Complete Guide to Linux Privilege Escalation for Penetration Testers](https://writes.eshansingh.in/linux-privesc): Comprehensive walkthrough of Linux permissions and every major privilege escalation vector including SUID/SGID binaries, sudo rules, capabilities, cron and systemd timers, shared library injection, and 2026 page cache corruption exploit analysis.
- [VulnHub: The Planets - Earth (Walkthrough & Exploit Analysis)](https://writes.eshansingh.in/vulnhub-earth): Comprehensive boot2root walkthrough of VulnHub Earth: SSL certificate DNS reconnaissance, repeating-key XOR cryptanalysis in Python, admin command injection, and SUID binary reverse engineering on Fedora 33 x86_64.

## Key Technical Topics & Methodologies

- [Reconnaissance & OSINT](https://writes.eshansingh.in/): Network reconnaissance with arp-scan, nmap port auditing, and SSL Subject Alternative Name (SAN) certificate DNS extraction.
- [Cryptanalysis & Decryption](https://writes.eshansingh.in/vulnhub-earth): Repeating-key XOR decryption, known-plaintext cryptanalysis, and automated Python cryptanalysis scripts.
- [Web Application Exploitation](https://writes.eshansingh.in/vulnhub-earth): Command injection filter bypasses, bash reverse shell execution, and sensitive configuration discovery.
- [Linux Privilege Escalation](https://writes.eshansingh.in/linux-privesc): SUID/SGID binary analysis, sudo environment persistence, cron hijacking, systemd service tampering, and kernel exploit mitigation.

## Optional & Machine Discovery

- [XML Sitemap](https://writes.eshansingh.in/sitemap.xml): Machine-readable index of all published canonical URLs.
- [Robots Directives](https://writes.eshansingh.in/robots.txt): Machine access directives and crawling rules.