Didier Stevens

Wednesday 22 June 2011

Quickpost: Need a PoC to Test Your Security Setup? Not Necessarily…

Filed under: Quickpost,Vulnerabilities — Didier Stevens @ 13:30

People regularly ask me for a PoC (PDF or other type) to test their security setup. For example, they sandboxed Adobe Reader and now they want to test that Adobe Reader can’t write to sensitive Windows directories like system32.

Well, you don’t need a PoC to test your setup in this way. Just develop and compile a DLL that writes to system32, and inject it in the target process.

The problem however, is that not everybody has the skills to develop and compile such a DLL. But almost everybody can write a VBScript that accomplishes the same. Here’s a one-liner that creates test.txt in system32:

CreateObject("Scripting.FileSystemObject").CreateTextFile("c:\windows\system32\test.txt")

But how do you get the target process to execute this script? That is something I worked out 2 years ago: bpmtk: Injecting VBScript. In a nutshell: I developed a DLL that once injected into a process, instantiates a VBScript engine and executes the provided script.

Monday 13 June 2011

EMET Article

Filed under: Vulnerabilities — Didier Stevens @ 0:00

(IN)SECURE Magazine published my article on Microsoft’s Enhanced Mitigation Experience Toolkit.

It contains many details I’ve yet to discuss on this blog.

 

Monday 6 June 2011

Update: vs.py

Filed under: Hardware,My Software — Didier Stevens @ 18:46

I’ve updated my Python program to take surveillance pictures from IP-cameras. This updated version is multi-threaded. For each picture to retrieve, you can specify a thread.

Each line in vs.config requires a 4th parameter now, the name of the thread:

Hall.jpg    http://192.168.1.1/IMAGE.JPG    -    Thread1

This name can be anything. If you use the same name for different pictures, then these pictures will be retrieved sequentially by this thread.

vs_v0_4.zip (https)

MD5: A2AFAD9E581798F1D986A0AE9DF64577

SHA256: C3AC4892A71DF79E3BA87714CB6323D157C7E74C838EDE81013C96DD4EAD0238

Wednesday 25 May 2011

Malicious PDF Analysis Workshop Screencasts

Filed under: Forensics,PDF — Didier Stevens @ 15:58

After giving my Malicious PDF Analysis workshop at Hack In The Box Amsterdam, I decided to produce a screencast for each exercise (there are 20 exercises). You can find the first screencasts here. More will be produced soon.

Materials you’ll need for the exercises:

Tuesday 17 May 2011

Another PDF Puzzle

Filed under: Forensics,PDF,Puzzle — Didier Stevens @ 8:23

As I’m going to give my workshop on analysis of malicious PDFs at HiTB Amsterdam this Thursday, I thought I would share a PDF puzzle/challenge I made for BSidesLondon.

You can download it here.

And as there is write-up for the solution to this puzzle on a blog, I’ll link to this in the comments next week. Since you can just Google the solution, there is no prize this time.

Thursday 12 May 2011

BackTrack 5 Includes PDFiD and pdf-parser

Filed under: Forensics,PDF — Didier Stevens @ 21:13

You probably noticed the release of BackTrack 5.

But did you notice the inclusion of my PDFiD and pdf-parser tools?

You can find them under /pentest/forensics/pdfid and /pentest/forensics/pdf-parser.

Wednesday 27 April 2011

Suspender.dll

Filed under: My Software — Didier Stevens @ 16:12

When the suspender DLL is loaded inside a process, it will wait for 60 seconds and then suspend all the threads of the host process. If you want another delay, just change the name of the file by appending the number of seconds to sleep. For example, suspender10.dll will wait for 10 seconds before suspending the process.

To resume the process, you can use Process Explorer.

I’ve used this DLL to analyze malware and to disable some unwanted programs without killing them.

And from now on, I’ll try to release 32-bit and 64-bit versions of my tools.

Download:

Suspender_V0_0_0_3.zip (https)

MD5: C87FCAB2586C6154B58FB0F95FBB1FBE

SHA256: 56D0C641569E99AC31C7590DE513025E21166747565B73C5EBE34346616FFB2F

Tuesday 19 April 2011

Signed Spreadsheet with cmd.dll & regedit.dll

Filed under: Hacking,My Software — Didier Stevens @ 14:05

Remember my Excel with cmd.dll & regedit.dll?

Paul Craig has a signed version of my spreadsheet on his iKAT site. Download ikat3.zip and look for officekat.xls.

These signed macros are handy when you’re working in a restricted environment that requires Office macros to be signed.

Wednesday 6 April 2011

LockIfNotHot

Filed under: Hardware — Didier Stevens @ 8:34

When Phidget came out with this new IR temperature sensor, a lightbulb went off. This sensor measures temperature without contact. Point it to the chair in front of your computer, and it will measure your body temperature. Or the temperature of your chair, if you’re not sitting in front of your computer.

And that’s the idea: I wrote a program that locks your Windows workstation when you leave your chair (e.g. when the temperature drops).

In this screenshot, LockIfNotHot is configured to lock the workstation when the temperature drops below 25°C during 3 seconds and there is no user input during 2 seconds.

Once the workstation is locked, you need to provide your Windows account password to unlock it.

Download:

LockIfNotHot_V0_0_1.zip (https)

MD5: 188BE76E0A5BCCA26A8736F8F0C4061C

SHA256: CA915265D3B224DF3AA95E5C59B7C0E7EDF239DF50FC1C03F2C991A8B1800AD2

Monday 21 March 2011

Windows Security Center: Under the Hood

Filed under: Windows 7,Windows Vista — Didier Stevens @ 10:29

I’m sure you’ve seen the following warning before:

But have you ever wondered where the Windows Security Center gets its info? (BTW, Microsoft renamed it Windows Action Center in Windows 7).

It gets the information from the Windows Management Instrumentation interface, and more precisely, the WMI name spaces \root\SecurityCenter and \root\SecurityCenter2. I wrote a small script to display this info:

You can download the script here.

It’s also possible to modify this WMI information. Say you’ve uninstalled an antivirus program, but that it still shows up in the Windows Security Center. Then you can delete the WMI information with utility wbemtest.exe.

Start wbemtest (if you’re on Windows Vista or 7, you need to elevate wbemtest) and click on connect.

Type the name space you want to change: \root\SecurityCenter or \root\SecurityCenter2 (SecurityCenter2 is a recent addition). And then connect.

Click onEnum Classes…

Then click OK

Then double-click the type of information you want to change. Here we change AntiVirusProduct:

Then click Instances

And now you can change the information. Here we delete it:

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