How to APT EP.1: Bypassing XDP and TC: Stealthy Connection Interception via BPF SK_LOOKUP
While most offensive eBPF techniques rely on XDP or TC to intercept raw network packets, Linux 5.6+ introduced BPF_PROG_TYPE_SK_LOOKUP, a hook operating at the socket dispatch layer. By attaching a 28-line BPF program directly to a network namespace, an attacker can silently redirect incoming TCP SYN requests to a backdoor socket without modifying packets, recalculating checksums, altering iptables rules, or leaving wire-level artifacts. This post breaks down how the technique works, common implementation traps, why it evades conventional EDR checks, and how defenders can audit for it.
Jul 30, 2026
16 min
220 views Cacheghost: Executing code from the kernel page cache
A file-backed executable mapping where the page content diverges from the backing file.
Jul 30, 2026
5 min
184 views I Spent a Week Fuzzing the BPF Verifier's New Circular Number System
I spent the better part of a week reverse-engineering Meta's ~3500 line refactoring of the BPF verifier's bounds tracking, the "circular number" (or cnum) rework that landed in Linux 7.0. I built a fuzzer, ran a quarter million random tests, traced through the linked register propagation by hand, disassembled my running kernel's vmlinux to check for backports, and generally went deeper into `kernel/bpf/verifier.c` than any sane person should.
Jul 29, 2026
4 min
107 views DCOM Permission Misconfiguration in WaaSMedicSvc Enables Unprivileged PPL Process Access
The Windows Update Medic Service (WaaSMedicSvc) is configured with overly permissive DCOM LaunchPermission rights, granting standard users the ability to instantiate COM objects within a Protected Process Light (PPL) service running as LocalSystem. The service, which operates with LaunchProtected=2 (PPL), exposes the WaaSRemediation COM object with LaunchPermission SDDL that includes Everyone (WD) and Interactive User (IU) with execute rights. This configuration allows unprivileged users to communicate across the PPL security boundary and execute methods in SYSTEM context. While prior research demonstrated exploitation of this attack surface via TypeLib hijacking, this finding identifies a distinct unprivileged access vector. Remediation involves restricting DCOM LaunchPermission to SYSTEM and Administrators only.
How Windows Delivery Optimization's Trust Chain Can Be Broken Before It Starts
Windows Delivery Optimization's security model, chunk hashes, peer banning, retry logic, all of it flows from a single in-memory structure called the Pieces Hash File. Control that file, and every downstream verification check works in your favor. This research traces how to get there: from the DLL, through the unpinned SSL channel, to the third-party CDN infrastructure serving that file to every Windows 11 machine on the planet.