I'm setting up Modsecurity, and I have noticed that some sensitive data (credit card numbers) ends up in the log. How should I prevent this? Preferably I would want it logged, but with the sensitive data mangled.
Example of a sensitive line in access.log
id_offer=28&ch_name=%27+or+1%3D1&ch_address1=Korvstolsv%E4gen+2&ch_address2=&ch_zip=756+48&ch_city=STOCKHOLM&ch_email=aslask%40test.net&ch_phone=018-9999999&cardno=1234456712342345&cvc=123&expire_month=--&expire_year=--&send=Avbryt
Maybe it could be like this instead? (Scroll to right. The sensitive fields are cardno and cvs.)
id_offer=28&ch_name=%27+or+1%3D1&ch_address1=Korvstolsv%E4gen+2&ch_address2=&ch_zip=756+48&ch_city=STOCKHOLM&ch_email=aslask%40test.net&ch_phone=018-9999999&cardno=manglemanglemangle&cvc=xxx&expire_month=--&expire_year=--&send=Avbryt
An alternative would be to completely remove that part if it contains sensitive data.
Because of a comment that I should use POST instead of GET, this was a POST.
--36b1f462-A--
[30/May/2017:19:06:55 +0200] WS2mrwpABwsAACy1A9wAAAAG 185.624.636.40 61597 610.64.66.8 445
--36b1f462-B--
POST /wb/e/check.php HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: sv-SE,sv;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate, br
Content-Type: application/x-www-form-urlencoded
Content-Length: 216
Referer: https://example.com/wb/e/auth.php
Connection: keep-alive
Upgrade-Insecure-Requests: 1
--36b1f462-C--
id_offer=28&ch_name=%27+or+1%3D1&ch_address1=Korvstolsv%E4gen+2&ch_address2=&ch_zip=756+48&ch_city=STOCKHOLM&ch_email=aslask%40test.net&ch_phone=018-9999999&cardno=1234456712342345&cvc=123&expire_month=--&expire_year=--&send=Avbryt
