InfoSect's Month of Pointless Bugs (#8)


Dr Silvio Cesare

InfoSect, Canberra's hackerspace, regularly runs public group sessions to perform code review and vulnerability discovery. Over the next 30 days, I'll highlight the source code of 30 unknown vulnerabilities.

Bug #8

In bsdgames/hack, dropping privs can potentially fail similar to Bug #3 http://blog.infosectcbr.com.au/2018/02/infosects-month-of-pointless-bugs-3.html

bsdgames/hack/hack.pager.c int child(int wt) { int status; int f; f = fork(); if (f == 0) { /* child */ settty((char *) 0); /* also calls end_screen() */ (void) setuid(getuid()); (void) setgid(getgid()); +++ doesn't check for errors ... #ifdef UNIX #ifdef SHELL int dosh() { char *str; if (child(0)) { if ((str = getenv("SHELL")) != NULL) execl(str, str, (char *) 0); else execl("/bin/sh", "sh", (char *) 0); pline("sh: cannot execute."); exit(1); } return (0); } #endif /* SHELL */

Popular posts from this blog

Pointer Compression in V8

Image
Syed Faraz Abrar @farazsth98   Summary In this blog post, I will provide some details on how the Chromium developers implemented pointer compression in V8. I will also talk about what this means from an exploit development perspective. Introduction I’ve been an intern at InfoSect for the past couple of weeks now, and in this time, I’ve had to do a bunch of security related research into both V8 and Spidermonkey. One of the things that I spent a short amount of my time on was pointer compression in V8. I hadn’t heard of the term at all until Bruno Keith ( @bkth_ ) mentioned it on twitter some time in December last year. The V8 developers also made a blog post to celebrate V8 v8.0 where they mentioned that implementing pointer compression had allowed them to save up to 40% in usage of heap memory! That’s a big improvement, so let’s take a look at what pointer compression is and what it means from an exploit developer’s perspective. Disclaimer This is not intended to
Read more

C++ Memory Corruption (std::string) - part 4

  Summary This is the next part of the C++ memory corruption series*. In this post, we'll look at corrupting the std:string object in Linux and see what exploitation primitives we can gain. * https://blog.infosectcbr.com.au/2020/08/c-memory-corruption-part-1.html * https://blog.infosectcbr.com.au/2022/01/c-memory-corruption-stdvector-part-2.html  *  https://blog.infosectcbr.com.au/2022/03/c-memory-corruption-stdlist-part-3.html Author: Dr Silvio Cesare Introduction C++ is a common language for memory corruption. However, there is much more literature on exploiting C programs and little on C++ programs. C++ presents new classes, objects, and data structures which can all be effectively used for building exploitation primitives. In this post, we'll look at corrupting the std::string class and see what specific primitives we can obtain. std::string We note that the object stored in memory for a basic string consists firstly of the backing pointer to the string contents. Se
Read more

C++ Memory Corruption (std::vector) - part 2

Summary This is the 2nd part of the C++ memory corruption series*. In this post, we'll look at corrupting the std::vector class in Linux and see what exploitation primitives we can gain. We'll see that we can build arbitrary read/write primitives. * https://blog.infosectcbr.com.au/2020/08/c-memory-corruption-part-1.html   Author: Dr Silvio Cesare Introduction C++ is a common language for memory corruption. However, there is much more literature on exploiting C and not C++ programs. C++ presents new classes, objects, and data structures which can all be effectively used for building exploitation primitives.  In this post, we'll look at the std::vector class and see what specific primitives we can obtain.  Let's start by looking at /usr/include/c++/bits/stl_vector.h namespace std _GLIBCXX_VISIBILITY ( default ) { _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX_BEGIN_NAMESPACE_CONTAINER /// See bits/stl_deque.h's _Deque_base for an explanation. template < typename
Read more