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1. Ollydbg For Macvirtuallasopa Mac
2. Ollydbg For Macvirtuallasopa 2
3. Ollydbg For Macvirtuallasopa Full
4. Ollydbg For Macvirtuallasopa Windows

You are downloading OllyDbg, version 2.01. Each download we provide is subject to periodical scanning, but we strongly recommend you check the package for viruses on your side before running the installation. This download is absolutely FREE. The contents of the download are original and were not modified in any way. OllyDbg is a 32-bit assembler level analyzing debugger for Microsoft Windows. Emphasis on binary code analysis makes it particularly useful in cases where source is unavailable. Ollydbg shows you a lot of data, but for now just notice the Assembly Code in the top left pane, and the Paused message in the lower right. When you load a program into Ollydbg, it starts in a 'Paused' state, with the Assembly Code window showing the first instruction. Running Putty in Ollydbg In Ollydbg, from the menu bar, click Debug, Run.

What You Need

A Windows machine, real or virtual. I used a Windows Server 2008 virtual machine.

Purpose

To modify a Windows EXE file and save an altered version.This gives you practice with very simple features of theOllydbg debugger.

Get putty.exe

If you are using the machine handed outby your instructor, putty.exe is inthe Downloads folder.

If you are using some other machine,get it here:

Verifying the SHA256 Hash

Run Hashcalc on putty.exe andconfirm that the SHA256 value matchesthe value shown below.

Running Putty

Double-click putty.exe. PuTTY opens, as shown below.

If PuTTY won't start, right-click it, click Properties,and click Unblock.

In the 'Host Name (or IP address)' box, type

ad.samsclass.info

At the bottom, click the Open button.

A black box opens, and shows a 'login as:'prompt, as shown below.

You could connect to a server at this point,but that's not the point of this project.We will alter this program to do other thingsinstead of printing 'login as'.

Close the Putty window.

Starting Ollydbg

Click Start. Search for Ollydbgand start it.

In Ollydbg, from the menu bar, clickFile, Open. Navigate toputty.exe and open it.

Ollydbg opens, as shown below. If yourscreen doesn't look like this, clickView, CPU and maximize theCPU window.

Ollydbg shows you a lot of data,but for now just notice theAssembly Code in the topleft pane, and the Pausedmessage in the lower right.

When you load a program into Ollydbg,it starts in a 'Paused' state,with the Assembly Code window showingthe first instruction.

Running Putty in Ollydbg

In Ollydbg, from the menu bar,click Debug, Run.

A Putty window opens,but it's behind the Olly window.At the bottom of the screen,in the taskbar, click the'PuTTY Configuration'button to bring the PuTTY windowto the front,as shown below.

Click in the Putty window.In the 'Host Name (or IP address)' box, type

ad.samsclass.info

At the bottom, click the Open button.The 'login as' message appears,as shown below.

Putty is running, but it's under the controlof Ollydbg, so we can modify its execution.

Finding the 'login as' Code

Close the Putty window. A boxasks 'Are you sure...' ClickOK.

In Ollydbg, from the menu bar,click Debug, Restart.

In Ollydbg, in the 'Assembly Code'pane, right-click. Point to'Search for'. Click'All referenced text strings',as shown below.

A'Text strings referenced in putty:.text'window opens, showing all thestrings in the program.

To make this text easier to read,right-click, point toAppearance,Font, and click'OEM Fixed Font'.

Right-clickin that window, and click'Search for text',as shown below.

In the 'Enter text to search for' box,type

login as

as shown below. Check the'Entire scope' box.

Click OK.

Ollydbg finds the ASCII string 'login as',and the instruction that uses it,as shown below. This instructionis at address 00417053.

Right-click again, and click'Search next'.

Ollydbg finds another line of codethat uses this string,as shown below. This instructionis at address 0041CB6E.

Right-click again, and click'Search next'.

A message appears at the bottom of thewindow saying 'Item not found'.There are only two commands in theprogram that use this string.

Using Breakpoints

We'll set breakpoints at those instructionsto see which one is used when logging into an SSH server.

In the 'Text strings referenced in putty:.text'window,right-click again, and click'Search text'. In the'Enter text to search for' box,click OK.

The instruction at 00417053 appears again.Right-click this instruction andclick 'Toggle breakpoint',as shown below.

The address turns red,as shown below, to indicate thatthere's a breakpoint here.

Right-click again, and click'Search next'. The instructionat address 0041CB6E appears.Right-click it andclick 'Toggle breakpoint'.

The address turns red,as shown below.

In Ollydbg, from the menu bar,click Debug, Restart.

A box pops up warning you that'Process 'putty' is active'.Click Yes.

In Ollydbg, from the menu bar,click Debug, Run.

A Putty window opens. Bring it to thefront, as shown below.

Click in the Putty window.In the 'Host Name (or IP address)' box, type

ad.samsclass.info

At the bottom, click the Open button.

A black window opens and closesquickly, and the programstops,as shown below.

The program stopped at instruction0041CB6E, as shown in the image above.

We'll use this instruction to hijack theprogram's execution.

Removing the Breakpoints

We don't need the breakpoints any more,so we'll remove them.

In Ollydbg, from the menu bar,click View, Breakpoints.

A 'Breakpoints' window opens, showingtwo breakpoints.

Right-click the first breakpoint and clickRemove, as shown below.

Repeat the process to removethe other breakpoint. Close the'Breakpoints' window.

Removing One Letter From the Message

In Ollydbg, in the CPU window, in theAssembly Code pane, right-click theinstruction at address 0041CB6Eand click Assemble,as shown below.

An 'Assemble at 0041CB6E' box appears,as shown below.

This shows the command at this location. It'sa PUSH instruction, placing the address467C7C onto the stack. That addresspoints to the letter 'l' in the ASCII string'login as: ', as shown on the right sideof the instruction line, outlined in greenin the image below.

In the 'Assemble at 0041CB6E' box, changethe last character to D,as shown below. This will move thepointer from the 'l' to the 'o' in thestring 'login as: '.

Click the Assemble button.

Click the Cancel button.

The message on the right now says'ogin as: ',as shown below.

Running the Modified Program

In Ollydbg, from the menu bar,click Debug, Run.

The black login window appears,with the message 'ogin as: ',as shown below.

When I did it, an error box alsopopped up saying 'Server unexpectedlyclosed network connection'. If that happens,just close the error box.

Saving the Modified .text Section

We have now changed an assembly languageinstruction; all executable code isin the .text section of the file.

In Ollydbg, in the top left pane of theCPU window, right-click, point to'Copy to Executable',and click 'All modifications',as shown below.

A 'Copy selection to executable file' boxpops up, as shown below.Click the 'Copy all'button.

A new window pops up, with a title ending in'putty.exe', as shown below.

Right-click in the new window and click'Save file'.

Save the file as puttymod.exe.

Ollydbg For Macvirtuallasopa Mac

Running the Modified EXE

Close Ollydbg.

Double-click puttymod.exe.

In the 'Host Name (or IP address)' box, type

ad.samsclass.info

At the bottom, click the Open button.

A black box opens, and shows a 'ogin as:'prompt, as shown below.

Modifying the puttymod File

Open Ollydbg and load the puttymod.exefile.

In the top left pane of the CPU window,right-click, point to'Go to', and clickExpression,as shown below.

In the 'Enter expression to follow' box,enter

41CB6E

as shown below. Click OK.

Changing the Login Message

In the top left pane of the CPU window,right-click 00467C7D,as shown below. Point to'Follow in Dump' andclick 'Immediate constant'.

The Hex Dump pane, inthe lower left, shows the text'ogin as: ',as shown below.

In the Hex Dump pane,highlight 'ogin as:',as shown below. Right-click thehighlighted text.Point to Binary.Click Edit.

An 'Edit data at 00467C7D' boxopens,as shown below.

Click in the ASCII field, press Backspaceto move back to the start, andoverwrite the message with this text,as shown below:

BADNESS

Click OK.The modified text appears in redletters in the Dump,as shown below.

Saving the Modified ASCII Text

In Ollydbg, in the lower left 'Dump' pane of theCPU window, right-click and click'Copy to executable file',as shown below.

A boxwith a long title ending in'puttymod.exe'appears showing the modifiedfile, as shown below. Click theX in the top right of thatbox to close it.

A 'File changed' box appears, asshown below. Click Yes.

A 'Copy selection to executable file' boxpops up. Click the 'Copy all'button.

A new window pops up, with a title ending in'putty.exe', as shown below.

Right-click in the new window and click'Save file'.

Save the file as 'puttymod2.exe'.

Running the Modified EXE

Close Ollydbg.

Double-click puttymod2.exe.

In the 'Host Name (or IP address)' box, type

ad.samsclass.info

At the bottom, click the Open button.

A black box opens, and shows a'BADNESS:'prompt, as shown below.

Ollydbg For Macvirtuallasopa 2

Calculating the Hash (20 pts)

Calculate the CRC32 hash puttymod2.exe

Use the formbelow toget your points.

Sources

Backdooring PE Files - Part 1
Art of Anti Detection 2 – PE Backdoor Manufacturing
https://github.com/EgeBalci/Cminer
https://en.wikipedia.org/wiki/Code_cave
http://stackoverflow.com/questions/787100/what-is-a-code-cave-and-is-there-any-legitimate-use-for-one
The Beginners Guide to Codecaves
Reversing with Ollydbg debugger

Ollydbg For Macvirtuallasopa Full

Ollydbg For Macvirtuallasopa Windows

Ollydbg 'Copy all modifications to executable' doesn't copy all modificationsRevised 1-7-19