Another Olly Plugin from Exetool member taos.

This plugin allows you to search for a given text when automatically
stepping through the debugged program.

When the plugin is enabled, it will step automatically through the debugged
program once a step command (like Step Into) is issued.
Enabling the plugin is done with the “Options” menu command.

After enabling, press F7 to start.

After each step, the plugin will check which registers have changed.
If a changed register points to an ASCII string, it is logged.
If a search string has been defined and it is contained in the ASCII string
pointed to by the register or the Information pane, the stepping is paused.
Comparison is case sensitive.

A search string is defined by entering it with the “Options” menu command.
It is remembered in the OllyDbg INI file.
Entering an empty string disables the break on string command.
OllyStepNSearch can search in strings pointed to by registers (search in registers toggle)
and it can search in the Information pane of the CPU window (search in information toggle).
Read the “Information window” help section of the OllyDbg v1.10 help file if you’re not familiar
with the Information pane.

If the search string is not found, debugging is resumed. If the current address
is lower than the limit address (by default 0×10000000) a step into command is
issued. A step over command is issued if the current address is higher than the
limit address, or if the current command is a call/jump to an address higher
than the limit address.
The limit address can be changed in the Options dialog.

The plugin can be disabled automatically when the search string is found (Disable after break toggle).
I added this option because I usually want to single step after finding the search string,
but often forgot to disable the plugin before single stepping.

Restarting the debugged program disables the plugin.

Debugging example:

Start OllyDbg and load the ftp.exe program (in system32 directory)
Start the OllyStepNSearch plugin “Options” menu command
Enter “google” as Search string (without the double quotes, of course)
Enable StepNSearch
Click OK
Press F7 to start debugging
Go to the FTP window and type “open google.com” and press enter
The StepNSearch plugin will stop debugging when a register points to a string containing google. On my Windows XP SP2, this happens when EAX points to “open google.com”.
You can continue with F7 and see how ftp.exe parses the “open google.com” command

Regards,

Yes, I've used this plugin at some occasions, and it is indeed a very good option when you cannot seem to find any good "direct" way to pinpoint the code you're interested in.

Doesn't OllyDbg already have this conditional breakpoint functionality for inspecting memory pointers in registers?

This plugin traces every instruction, so it also helps you find the good spots to breakpoint.

It also inspects all registers and stack automatically, searching for the string you specify, without any unnecessary configuration effort.

For reference I thought I'd add the author's homepage - http://blog.didierstevens.com/

Although there haven't been any updates recently he does post the latest version of his tools to his blog. If anyone wishes to keep up to date with the plugin, this is where to do it.