'failed to parse a modsec variable' on LiteSpeed

Issue

LSWS users may see errors like

2022-10-08 15:51:43.110779  ERROR   [ModSecurity] failed to parse a modsec variable. while parsing: %{REQUEST_COOKIES.pwg_id}
2022-10-08 15:51:43.110937  ERROR   [ModSecurity] failed to parse a modsec variable. while parsing: %{REQUEST_COOKIES.pwg_id}

in the logs.

Environment

• Imunify360
  
• LSWS
• ModSecurity

Solution

It is safe to disregard those errors in accordance with the LSWS documentation:

The above error messages simply mean the given variables are not supported by LSWS yet. The errors can simply be ignored. We periodically review our mod_security engine and frequently add new support. Stay tuned.

Cause

Not all variables are supported by LSWS, unlike Apache.

Useful links

• LSWS Unsupported Variable Error.