Key Logging

Key logging is one of the most powerful spyware techniques. Using a hook on the keyboard handler within the kernel, the rootkit can sniff pass phrases, including those used to unlock private keys in a cryptographic system. A keystroke log does not take up much space and can

•	Table of Contents
log activity for days or weeks before the attacker needs to pick up the log file. The key stroke
•	Index

logger can detect control key combinations as well as normal characters in upper or

ExploitinglowercaseSoftware. TypicallyHoweachto BreakkeystrokeCode is referred to as a scancode. A scancode is the numerical

representation of the keystroke in memory.

ByGreg Hoglund,Gary McGraw

Key loggers have taken many forms over the last decade, and the technique depends on the

Publisher: Addison Wesley

OS being infected. On many older Windows and DOS machines, hooking interrupt 9 was

Pub Date: February 17, 2004

enough to gather keystrokes. On Windows NT and beyond, the keystroke monitor must be

ISBN: 0-201-78695-8

installed as a driver. Similar conditions exist under Linux.

Pages: 512

From the attacker's perspective, the following two issues remain: how the data are stored in the file, and who they are sent to over the network. If keystrokes are stored in plain text, then those keystrokes are available to all rogue interlopers. If they are sent to someone's e- mail address, then that person will be interrogated. These issues can be resolved using

cryptography. The keystrokes can be stored in public key-encrypted form, and they are How does software break? How do attackers make software break on purpose? Why are

broadcast over a publically readable yet obscure channel. A cryptotrojan attack that uses this firewalls, intrusion detection systems, and antivirus software not keeping out the bad guys?

approach was published by Young and Yung at IEEE Security and Privacy. What tools can be used to break software? This book provides the answers.

Exploiting Softwareis loaded with examples of real attacks, attack patterns, tools, and

LinuxtechniquesKeyusedLoggerby bad guys to break software. If you want to protect your software from attack, you must first learn how real attacks are really carried out.

A couple of Linux key loggers have been published and the source code is available. These This must-have book may shock you—and it will certainly educate you.Getting beyond the

programs typically operate as loadable kernel modules (lkms). Under a UNIX system, the script kiddie treatment found in many hacking books, you will learn about

rootkit is usually already implemented as an lkm, so keystroke monitoring is just an

extension of the code. A Linux rootkit can hook into the character stream via the existing

keyboard driver or it can hook the interrupt handler for the keyboard directly. Why software exploit will continue to be a serious problem

When network security mechanisms do not work

Windows NT/2000/XP Key Logger

Attack patterns

Windows NT/2000/XP supports a special type of device driver called a filter driver. Most Reverse engineering

drivers under Windows are placed into chains. That is, each driver passes data to the next

driverClassicin hainattacks.A filteragainstdriverserversimplysoftwareinserts itself into a chain and siphons data or modifies

data in transit before passing control. There is already a keyboard driver chain into which a

itself

Surprising at acks against client software

rootkit can insert . Of course, the keyboard interrupt can also be hooked directly. Either

way, keystrokes can be captured and logged to a file, or sent over the network. Techniques for crafting malicious input

The technical details of buffer overflows

The Keyboard Controller Chip

Rootkits

On the system motherboard there are many hardware controller chips. These chips contain

Exploiting Softwareis filled with the tools, concepts, and knowledge necessary to break registers that can be read or written to. Typically, read/write registers on controller chips are

software.

calledports. A keyboard will usually contain an 8048 microprocessor. The motherboard will usually have an additional 8042 microprocessor. The 8042 will be programmed to convert scancodes from the keyboard. Sometimes the 8042 will also be handling PS/2 mouse input and possibly the reset switch for the CPU.

For the keyboard controller, we are interested in the following ports:

Port 0x60: 8048 chip, keyboard data register

Port 0x64: 8042, keyboard status register

To read characters from the keyboard, you must hook the keyboard interrupt. This will change depending on your OS. For a Windows system, the hook will most likely be int 0x31. Once IRQ 1 has fired, the data must be read from 0x60 before any more keyboard interrupts will occur.

Here is a simple handler for the keyboard interrupt:

•Table of Contents

•Index

Exploiting Software How to Break Code

ByGreg Hoglund,Gary McGraw

Publisher: Addison Wesley

Pub Date: February 17, 2004

ISBN: 0-201-78695-8

Pages: 512

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How does software break? How do attackers make software break on purpose? Why are firewalls, intrusion// do somethingd ection systems,with characterand antivinrusalsoftware not keeping out the bad guys? What tools can be used to break software? This book provides the answers.

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Exploiting Softwareis loaded with examples of real attacks, attack patterns, tools, and techniquesjmpused by badDWORDguysPTRto break[old_KEYsoftwareINT]. If you want to protect your software from attack, you must first learn how real attacks are really carried out.

This must-have book may shock you—and it will certainly educate you.Getting beyond the script kiddie treatment found in many hacking books, you will learn about

Why software exploit will continue to be a serious problem

When network security mechanisms do not work

Attack patterns

Reverse engineering

Classic attacks against server software

Surprising attacks against client software

Techniques for crafting malicious input

The technical details of buffer overflows

Rootkits

Exploiting Softwareis filled with the tools, concepts, and knowledge necessary to break

software.

Advanced Rootkit Topics

There isn't enough room in this book to cover all the advanced tricks that can be performed by rootkits. Fortunately, there are many resources and articles available on the Internet that cover this subject. One great resource is Phrack Magazine (http://www.phrack.com). Another

•	Table of Contents
is the BlackHat security conference (http://www.blackhat.com). We briefly describe a small
•	Index

set of advanced techniques here, providing references to more information when applicable.

Exploiting Software How to Break Code

ByGreg Hoglund,Gary McGraw

Using a Rootkit as a Debugger

Publisher: Addison Wesley

A kernelPub Date:rootkitFebruarydoesn't17, 2004have to be malicious. You can use one to keep watch on a system you own. OneISBN:great0-201-use78695of-8a rootkit is to replicate the functions of a debugger. A rootkit with a shell andPages:some512 debugging functions is really no different than a debugger like SoftIce. You can add a decompiler, the ability to read and write memory, and break point support.

Disabling Windows System File Protection

How does software break? How do attackers make software break on purpose? Why are

firewalls, intrusion detection systems, and antivirus software not keeping out the bad guys? Thewinlogon.exe process loads a few DLLs that are responsible for implementing system

What tools can be used to break software? This book provides the answers.

file protection. The file sfc.dll is loaded, followed by sfcfiles.dll. The list of files to be

protected is loaded into a memory buffer. A simple patch can be made to the code within

Exploiting Softwareis loaded with examples of real attacks, attack patterns, tools, and sfc.dll that will disable all file protection. The patch can be made using standard Windows

techniques used by bad guys to break software. If you want to protect your software from debugging APIs.[10]

attack, you must first learn how real attacks are really carried out.

[10] For more on this issue, see 29/A Labs publications for work by Benny and Ratter.

This must-have book may shock you—and it will certainly educate you.Getting beyond the

script kiddie treatment found in many hacking books, you will learn about

Writing Directly to Physical Memory

Why software exploit will continue to be a serious problem

A rootkit does not need to use a loadable module or Windows device driver. A rootkit can be

When network security mechanisms do not work

installed by simply writing to data structures in the kernel. An excellent article on windows

objects and physical memory is available in Phrack Magazine, Issue 59, Article 16: "Playing

Attack patterns

with Windows /dev/(k)mem" by crazylord.

Reverse engineering

KernelClassicBufferattacksOverflowsagainst server software

Surprising attacks against client software

Code in the kernel is subject to the same bugs that affect all other software. Just because

code is running in the kernel doesn't mean it's immune to stack overflows and other

Techniques for crafting malicious input

standard-issue exploits. In fact, several kernel-level overflows have been made public.

The technical details of buffer overflows

Exploiting a buffer overflow in the kernel is a bit tricky because exceptions in the kernel tend

to crash the machine or cause a "blue screen of death." Exploits of the kernel are especially Rootkits

noteworthy because they can directly infect a machine with a rootkit and they bypass all

security mechanisms. An attacker does not need administrative privileges or the ability to Exploiting Softwareis filled with the tools, concepts, and knowledge necessary to break

load a device driver if they can simply overflow the kernel stack. An article on kernel software.

overflows can be found in Phrack Magazine, issue 60, article 6: "Smashing The Kernel Stack

For Fun And Profit" by Sinan "noir" Eren.

Infecting the Kernel Image

Another way to get code into the kernel is to patch the kernel image itself. We illustrate in

this chapter a simple patch to remove security controls from the NT kernel. Any piece of code

can be modified in such a way. One needs to be sure to correct any integrity checks in the code, such as the file check sum. An article on patching the Linux kernel can be found in

Phrack Magazine, Issue 60, Article 8: "Static Kernel Patching" by jbtzhm.

Execute Redirection

•	Table of Contents
We also illustrate how to redirect execution under Windows. For a good discussion on how to
•	Index

perform execute redirection under Linux, see "Advances in Kernel Hacking II" in Phrack

Exploiting Software How to Break Code

Magazine, Issue 59, Article 5, by palmers.

ByGreg Hoglund,Gary McGraw

DetectingPublisher: AddisRootkitsn Wesley

Pub Date: February 17, 2004

There areISBN:several0-201-78695methods-8 to detect rootkits, all of which can be circumvented if the rootkit itself isPages:aware512of the trick. Patched memory can be detected by reading the call tables or functions and checking their values. Instructions can be counted during runtime and compared with a baseline. Any sort of behavior changes can, in theory, be detected. The key weakness is when the code that performs this sort of check lives on the same machine that has been compromised. At this point, the rootkit can subvert the code that performs the

check. An interesting trick to detect a rootkit is discussed in Phrack Magazine, Issue 59, How does software break? How do attackers make software break on purpose? Why are

Article 10, "Execution Path Analysis: Finding Kernel Based Rootkits" by Jan K. Rutkowski. A firewalls, intrusion detection systems, and antivirus software not keeping out the bad guys?

tool to detect rootkits in the Solaris kernel can be downloaded from

What tools can be used to break software? This book provides the answers. http://www.immunitysec.com.

Exploiting Softwareis loaded with examples of real attacks, attack patterns, tools, and techniques used by bad guys to break software. If you want to protect your software from attack, you must first learn how real attacks are really carried out.

This must-have book may shock you—and it will certainly educate you.Getting beyond the script kiddie treatment found in many hacking books, you will learn about

Why software exploit will continue to be a serious problem

When network security mechanisms do not work

Attack patterns

Reverse engineering

Classic attacks against server software

Surprising attacks against client software

Techniques for crafting malicious input

The technical details of buffer overflows

Rootkits

Exploiting Softwareis filled with the tools, concepts, and knowledge necessary to break

software.