Mod Security FAQ for LiteSpeed Web Server

Yes, but please make sure when using @inspectFile with a 3rd-party scanner, that the script returns 0 for block , and 1 for continue/pass.

Example code from the mod_security reference manual:

$output = "0 Unable to parse clamscan output [$1]";

if ($error_message =~ m/: Empty file\.?$/) {
    $output = "1 empty file";
}
elsif ($error_message =~ m/: (.+) ERROR$/) {
    $output = "0 clamscan: $1";
}
elsif ($error_message =~ m/: (.+) FOUND$/) {
    $output = "0 clamscan: $1";
}
elsif ($error_message =~ m/: OK$/) {
    $output = "1 clamscan: OK";
}
print "$output\n";

No. LiteSpeed Web Server only supports the serial mode for audit logging.

A concurrent-mode audit log is only useful for servers like Apache which is process-driven and has multiple processes that may change UID. LiteSpeed is event-driven, and as such, concurrent mode is not needed.

Sometimes you may see some errors like the following:

2018-10-08 15:51:43.075081  ERROR   [ModSecurity] FILES:import_file "@rx <": Rule not supported.
2018-10-08 15:51:43.077152  ERROR   [ModSecurity] failed to parse a modsec variable. while parsing: %{TIME_EPOCH}
2018-10-08 15:51:43.077934  ERROR   [ModSecurity] unknown server variable while parsing: FILES:import_file
2018-10-08 15:51:43.077942  ERROR   [ModSecurity] FILES:import_file "@contains <": Rule not supported.
2018-10-08 15:51:43.081368  ERROR   [ModSecurity] unknown server variable while parsing: MATCHED_VARS_NAMES
2018-10-08 15:51:43.081385  ERROR   [ModSecurity] MATCHED_VARS_NAMES "@rx ^ARGS:AGENDA_EXT_(?:NAME|SRC|COLOR)__[\d]{1}$" "t:none": Rule not supported.
2018-10-08 15:51:43.104981  ERROR   [ModSecurity] unknown server variable while parsing: FILES:file
2018-10-08 15:51:43.105000  ERROR   [ModSecurity] FILES:file "@contains <" "t:none,t:urlDecodeUni,t:htmlEntityDecode": Rule not supported.
2018-10-08 15:51:43.110779  ERROR   [ModSecurity] failed to parse a modsec variable. while parsing: %{REQUEST_COOKIES.pwg_id}
2018-10-08 15:51:43.110937  ERROR   [ModSecurity] failed to parse a modsec variable. while parsing: %{REQUEST_COOKIES.pwg_id}

or

2018-09-26 16:57:36.700054 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/001_i360_1_generic.conf
2018-09-26 16:57:36.700631 [ERROR] [ModSecurity] unknown server variable while parsing: FILES_COMBINED_SIZE
2018-09-26 16:57:36.700669 [ERROR] [ModSecurity] FILES_COMBINED_SIZE "@gt %{tx.combined_file_sizes}" "t:none": Rule not supported.
2018-09-26 16:57:36.703233 [ERROR] [ModSecurity] unknown server variable while parsing: MATCHED_VARS_NAMES
2018-09-26 16:57:36.703266 [ERROR] [ModSecurity] MATCHED_VARS_NAMES "TX:paramcounter_(.*)" "capture": Rule not supported.
2018-09-26 16:57:36.706773 [ERROR] [ModSecurity] unknown server variable while parsing: ARGS_COMBINED_SIZE
2018-09-26 16:57:36.706802 [ERROR] [ModSecurity] ARGS_COMBINED_SIZE "@gt %{tx.total_arg_length}" "t:none": Rule not supported.
2018-09-26 16:57:36.707414 [ERROR] [ModSecurity] unknown server variable while parsing: REQBODY_ERROR
2018-09-26 16:57:36.707456 [ERROR] [ModSecurity] REQBODY_ERROR "!@eq 0" "msg:'Failed to parse request body.||MVN:%{MATCHED_VAR_NAME}||T:LITESPEED||MV:%{MATCHED_VAR}||PC:%{PERF_COMBINED}',tag:'i360',id:88139653,rev:'1',maturity:'9',accuracy:'9',phase:request,pass,t:none,tag:'noshow',severity:7,tag:'o'": Rule not supported.
2018-09-26 16:57:36.708774 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/002_i360_2_bruteforce.conf
2018-09-26 16:57:36.709169 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/003_i360_3_wallarm.conf
2018-09-26 16:57:36.709222 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/004_i360_4_webshells.conf
2018-09-26 16:57:36.907572 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/005_i360_5_custom.conf
2018-09-26 16:57:36.908424 [INFO] Processing config file: 
/etc/apache2/conf.d/modsec_vendor_configs/imunify360_full_litespeed/100_Init_Initialization.conf

We try to keep LSWS compatible with the latest mod_security 2.5(and above) and gotroot rules. LSWS supports most of these rules. We attempt not to miss any really important features/rules used in the real world, and we regularly add support for more features based on our user feedback. However, because of the complexity and fluctuating nature of these security rules, it is not possible to be 100% compatible with Apache at any one time.

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.

When you use SecDebugLogLevel, SecAuditLogParts or SecAuditLog within the LocationMatch directive, you may see the following errors on LSWS:

Directive 'SecDebugLogLevel' is not allowed in current context.
Directive 'SecAuditLogParts' is not allowed in current context.
Directive 'SecAuditLog' is not allowed in current context.

LiteSpeed Web Server does support the LocationMatch context, however the above three directives may not be configured within it. On LSWS, audit log can only be set at the server level, and the debug log level can be set at vhost level. We have no plans to make these directives available at the matching context level, as it would be counterproductive to the optimization applied to the engine.