dhulliger

@ruheabteil.ch

dad, screaming at computers and climbing rocks

🧵 Thread on beautiful data centers: MareNostrum 4 (Barcelona SCC): Often called "the most beautiful data center in the world," this facility is housed inside the Torre Girona Chapel, a deconsecrated 19th-century church. When fully installed, it will have a peak performance of 13.9 Petaflops.

Bild

cut my heap into pieces, this is my crash report: allocation, no alignment don't give a fuck if it faults on assignment this is fatal abort()

Heard of #ContextJail? It's a nasty new technique: puts target thread into ⓪ deadloop, for as long as you can afford. Requires THREAD_GET_CONTEXT right. The gist? Just spam NtGetContextThread(tgt).😸 Target will be jailed, running nt!PspGetSetContextSpecialApc 🔁. Src & binary in [ALT]. Usecases: ⤵️

Screenshot of contextjail.exe running with default arguments.


Highlighted:

* prisoner thread (latched to CPU1 with priority 15) couldn't run for the entire test duration (30 seconds).

* 99 jailer threads (latched to 6/8 processors, CPU2..CPU7) were using 20% of total CPU time.


Overlay: pseudo-ASSCII art with prisoner thread and 6 jailer threads (guards), spamming NtGetContextThread to block the prisoner.


Source and compiled binary:
https://pastebin.com/pBJcGp1y

The craziest file I made & visualized recently was combining the Doom PDF with a DOS & Windows (EXE & PE) polyglot. It runs Doom on OS from 1993 until today, and Chrome-based PDF viewers! You can make it an HTML/JS polyglot too to run on most browsers! (3/3)

The ultimate Doom polyglot, dissected: DOS executable, Windows Portable Executable, and PDF for Chrome via JavaScript! With offsets, explanations and snippets from the file.