Jump to content
View in the app

A better way to browse. Learn more.
Tuts 4 You

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

OllyDbg v1.10 And Hardware Breakpoints

waliedassar
waliedassar
in Reverse Engineering Articles

Featured Replies

Posted

While playing with OllyDbg v1.10, i came across a weird behavior of OllyDbg v1.10, which was fixed in the latest version. The problem lies in the way OllyDbg sets hardware breakpoints.

At 0x4D8D70, there is an array of four structures of type, t_hardbpoint.

Untitled.png

Each structure in this array holds information about each hardware breakpoint. Information includes hardware breakpoint address, type, and size. When you manually set a hardware breakpoint, this structure is filled, but the breakpoint is not immediately activated.

On the other hand, when an EXCEPTION_SINGLE_STEP or EXCEPTION_BREAKPOINT is received, information in the structures at 0x4D8D70 is copied to DR0 through DR3 overwriting old values in them, if there are any. The point here is that if you programmatically set a hardware breakpoint, single stepping will be enough to cause debug registers to be cleared.

Untitled.png

N.B. IDA pro and OllyDbg v2.0 behave normally with this scenario.

An executable demonstrating how to use this strange behavior to detect OllyDbg v1.10 can be found here.

http://ollytlscatch....s/demo_hwbp.exe

Original topic here.

http://waleedassar.b...reakpoints.html

very good walid u up egypt more and more

  • 3 weeks later...

nice info bro... :)

Create an account or sign in to comment

Go to topic listing

Configure browser push notifications
Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.