All Questions

Tagged with
Filter by
Sorted by
Tagged with
2
votes
1answer
89 views

Breakpoint in GDB hit 144 times before first call to function

I am working on a reverse engineering challenge and have a binary file. I know how to get the flag by changing the instruction flow after doing a strcmp so I jump to the function that prints the flag....
1
vote
0answers
73 views

How can a segfault happen during the libc exit call on Linux?

I'm relatively new to reverse engineering, and I've decided to practise using the challenges from pwnable.tw. Currently, I am working on the "Silver Bullet" challenge. While testing, I have noticed ...
2
votes
1answer
153 views

ROP chain: Buffer Overflow Return Pointer

I am trying to get a ROP exploit to work on Ubuntu 18.04 LTS 64bit. I have a 64 bit binary (Nx enabled, ASLR disabled) with vuln function as follows: public vuln vuln proc near var_100= byte ptr -...
0
votes
1answer
268 views

pwntools shellcode narnia2

I'm trying to solve the narnia2 challenge on overthewire. I read a guide for help and managed to overwrite the stack with A's using some python $(python -c "print 'A'*132 + '\xef\xbe\xad\xde'") ...
2
votes
1answer
84 views

obtaining string value from Unknown elf-x86-64 binary with gdb

I'm trying to find a string value stored in memory by a binary (possibly written in C) that won't show up when I perform "strings a.out". I have tried examining particular memory addresses of interest ...
7
votes
2answers
502 views

Reverse engineering Windows Defender's signature for Metasploit Framework's metsrv.dll

As a pentester for a consulting agency, it is part of our job to "evade" antivirus after gaining code execution on information systems. It is indeed necessary to prove exploitation of vulnerabilities, ...
1
vote
0answers
221 views

Stack buffer overflow SIGSEGV help

I've been going at this for a couple of days now working through trial and error but I can't seem to pinpoint exactly why I'm still getting a SIGSEGV. Here's the stdout of me stepping through the ...
1
vote
0answers
600 views

My core dump's backtrace stops to a signal handler, what can I do?

I obtained an ELF core dump that was provoked by fuzzing a proprietary server. As I do not have access anymore to the machine that hosted this server, and the server is part of a tightly coupled set ...
-1
votes
1answer
310 views

Disassembling code with Hopper

I'm trying to figure out what this code is doing. The first thing that I don't understand is the condition that tests if arg0's value is 0x2. I read that 0x2 in ASCII is STX (Start of text). Here's ...
1
vote
1answer
476 views

How can I change the values in esp?

0x08048785 <+344>: movl $0x0,0xc(%esp) 0x0804878d <+352>: movl $0x804896c,0x8(%esp) 0x08048795 <+360>: movl $0x8048973,0x4(%esp) 0x0804879d <+368>: movl ...
4
votes
4answers
1k views

Tools to show the registers and memory locations in use during execution?

I am looking for something that is like gdb but maybe with a GUI that can show all registers current values ans the current values of memory and things on the stack? Freeware is preferred. I have a ...
0
votes
2answers
556 views

What is the address of main() and how many bytes does it allocate on the stack for its frame size?

Here is my objdump -d output but I do not know where to look. I understand assembly but it is a little confusing trying to find out what the values of registers are at certain points. If anyone knows ...