Sanitizing Tomcat access log entries

In our logs we're seeing credit-card numbers due to people hitting some of the ULRs in our app with CC info (I have no idea why they are doing开发者_StackOverflow中文版 this). We want to sanitize this information (because of PCI considerations) and not even persist it to disk.

Hence, I want to be able to sanitize the log entry before it hits the log file. I've been looking at Tomcat Valves (Access Log Valve). Is this the way to go?

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I was able to solve this problem by extending AccessLogValve and overriding public log(java.lang.String message):

public class SanitizedAccessLogValve extends AccessLogValve {

    private static Pattern pattern = Pattern.compile("\\b(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\\d{3})\\d{11})\\b");

    /*
     This method will sanitize any cc numbers in the string and replace them with x's
    */
    private String sanitize(String string) {
        String sanitizedString = string;

        if(string != null) {

            StringBuffer buffer = new StringBuffer();
            Matcher matcher = pattern.matcher(string);

            while(matcher.find()) {
                MatchResult matchResult = matcher.toMatchResult();

                int start = matchResult.start();
                int end = matchResult.end();

                String matchedText = string.substring(start, end);

                matcher.appendReplacement(buffer, "xxxxxxxxxxxxxxxx");                
            }

            matcher.appendTail(buffer);

            sanitizedString = buffer.toString();
        }

        return sanitizedString;
    }

    @Override
    public void log(String message) {
        super.log(sanitize(message));
    }
}

You need to compile this into a jar, and then put that jar file in $CATALINA_HOME/lib.

Then in your server.xml:

<Valve className="my.valves.SanitizedAccessLogValve"
       directory="access_logs"  prefix="localhost." suffix=".log"
       pattern='%v %h %t "%r" %s %B %T "%{User-Agent}i"'/>