Author: dangokyo

Linux Kernel Exploitation Part 2: Buddy Allocator and SLUB Allocator

dangokyo1 Comment

Introduction

I will continue to talk about the exploitation of CVE-2017-7308. In this post, I will discuss the implementation details of buddy allocator and SLUB allocator in Linux-4.10.6. I will show how to put the victim object (struct packet_sock in this post) next adjacent to the vulnerable buffer (packet rv_ring buffer in previous post).
In [3], a general abstraction of Linux Kernel memory management is given as following picture. From the picture, we can find that two types of allocators (slab allocator and buddy allocator) are provided for Linux kernel functions. For both allocators, I will give some debugging info to give a straight view on how those objects are allocated and shaped in memory combined with some explanation on the source code.
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Linux Kernel Exploitation Part 1: Setting Up Debugging Environment

dangokyo3 Comments

Introduction

These days I think there is still necessity to write a tutorial series on Linux Kernel exploitation and hope to summarize the kernel exploitation techniques as following:
(1) Kernel Debugging
(2) Return-oriented-Programming in Kernel
(3) Kernel Mitigation: KASLR, SMEP, SMAP
(4) Kernel Space Memory Allocator: SLAB Allocator
In this post, I will introduce how to debug a Linux Kernel via CVE-2017-7308 [1], including setting up debugging environment, root cause analysis and exploit primitive analysis.
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Analysis on CVE-2017-3000

dangokyo1 Comment

Introduction

In this post, I will introduce CVE-2017-3000, a CVE assigned to us last year. We analyse the weak implementation of the PRNG in Flash Player, which is used for constant blinding in its JIT compiler. We find two methods circumventing the constant blinding. Furthermore, we give a detailed exploitation plan on how to insert desired value into JIT code even if constant blinding is in place as demonstrated on the cover page. In this post, I will give details on the design of the PRNG and full exploit based on CVE-2015-5122.
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Analysis on CVE-2015-5119

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Introduction

In this post, I will give a full COOP-like exploit based on CVE-2015-5119 as demonstrated on cover page. This post will contain two parts. The first part is about how to achieve arbitrary read/write primitive in 64-bit Flash. This part is based on [1][2] with some extra my own explanations. The second part is about how to achieve a COOP-like exploit with virtual function gadgets. I will discuss the dispatcher gadget, argument loading gadget and invoking gadget used in the exploit and pop up the calculator in the end. So I will skip the analysis of root cause of the vulnerability and focus on exploit development.
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Analysis on CVE-2016-9079

dangokyo3 Comments

Introduction

This is a use-after-use vulnerability in the firefox before 50.2 [1]. In this post, the exploit is a routine browser exploitation process. Since exploit [1] is a working exploit on windows platform, I rewrite the exploit to make it work on Linux platform and test some ideas on vtable reuse attacks. I use a chain of multiple virtual function gadgets to change memory protection and open a listening port or popping up calculator. The final exploit can be found on my github repo[3].
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MeePwnCTF 2018 Qual Pwn Coin Write-up

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Introduction

This is a very interesting challenge. Generally speaking, this is not a very hard challenge because its vulnerability is very obvious. However, this challenge is not that easy to exploit. First of all, the logic of the programme is very complicated and hard to reverse. Secondly, the exploitation involves multiple exploitation tricks in the end. Thirdly, the exploitation involves many double-to-integer conversion. Read More »