Marcos Diaz Margaruga

Windows system calls

...by stub

x86

Windows XP

B8 ?? ?? ?? ??                mov     eax, ??
BA 00 03 FE 7F                mov     edx, 7FFE0300h

Security Advisory – Java SE

Chris Frohoff – Qualcomm Information Security and Risk Management

Introduction

Affected Product(s): Java SE 6, Java SE 7
Fixed in: Java SE 7u25 (2013-06-18), Java SE 8 (2014-03-18)
Vendor Contact: [email protected]
Vulnerability Type: Unsafe Object Deserialization

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!

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Why stack grows down

Any running process has several memory regions: code, read-only data, read-write data, et cetera. Some regions, such as code and read-only data, are static and do not change over time. Other regions are dynamic: they can expand and shrink. Usually there are two such regions: dynamic read-write data region, called heap, and a region called stack. Heap holds dynamic memory allocations, and stack is mostly used for keeping function frames.

Both stack and heap can grow. An OS doesn't know in advance whether stack or heap will be used predominantly. Therefore, an OS must layout these two memory regions in a way to guarantee maximum space for both. And here is the solution:

Layout static memory regions at the edges of process's virtual memory
Put heap and stack on edges too, and let them grow towards each other: one grows up, one grows down

	using System;
	using System.Runtime.InteropServices;

	public class FxHook:IDisposable {

	const int nBytes = 5;

	IntPtr addr;
	Protection old;
	byte[] src = new byte[5];

	#include <windows.h>
	#include <subauth.h>
	#include <stdio.h>

	/* Windows structures */
	typedef struct _PEB_LDR_DATA {
	BYTE Reserved1[8];
	PVOID Reserved2[3];
	LIST_ENTRY InMemoryOrderModuleList;
	} PEB_LDR_DATA, *PPEB_LDR_DATA;