I searched the web and stumbled upon a good explaination on how to achive this.
First the .htaccess file:
# script that will store invalid login attempts
ErrorDocument 401 /logging.php
AuthName "My Password Protected Site"
AuthUserFile /<FULLPATH>/.htpasswd
AuthType Basic
Require valid-user
# Set REMOTE_USER env variable on 401 ErrorDocument
RewriteEngine On
RewriteBase /
RewriteCond %{ENV:REDIRECT_STATUS} ^401$
RewriteRule .* - [E=REMOTE_USER:%{ENV:REDIRECT_REMOTE_USER}]
Then the actual script that will do the logging:
if (isset($_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW'])):
$fp = fopen(MYLOGFILE, 'a+');
$password = $_SERVER['PHP_AUTH_PW'];
$username = $_SERVER['PHP_AUTH_USER'];
$time = date('y-m-d/H:i:s');
$request = $_SERVER['REDIRECT_URL'];
fwrite($fp, $time . "\t" . $request . "\t" . $username . "/" . $password . "\r\n");
fclose($fp);
endif;
ob_start();
header("HTTP/1.1 401 Authorization Required",1);
header("Status: 401 Authorization Required",1);
echo '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head><title>401 Authorization Required</title></head><body>
<h1>Authorization Required</h1>
<p>This server could not verify that you are authorized to
access the document
requested. Either you supplied the wrong
credentials (e.g., bad password), or your
browser doesn\'t understand how to supply
the credentials required . </p>';
exit();
The above workes just fine, and stores all invalid usernames and passwords in the specified logfile. I didn't get the example below to work, but it gave me some ideas on how to proceed.
Each line in the output file will hold something like this:
13-01-01/12:12:16 - /www/ - username/password
Log all .htaccess/.htpasswd logins