In my opinion CPU and memory limit for mod_substitute is missing here. The first problem in this module, is not limiting execution time and memory. It allow to local denial of service. We don't need convince that the use of PCRE is dangerous. So we need limit output time and memory in mod_substitute. -memory-exhaustion- AddOutputFilterByType SUBSTITUTE text/html Substitute "s|(.*(!?))||if" -memory-exhaustion- Result: Jul 5 13:16:04 127 /netbsd: UVM: pid 1768 (httpd), uid 1006 killed: out of swap -crash- AddOutputFilterByType SUBSTITUTE text/html Substitute "s|((.*){2222,}(.*){2222,})||iq" -crash- Result: [Mon Jul 11 02:57:29 2011] [notice] child pid 28 exit signal Illegal instruction (4) -cpu-exhaustion- AddOutputFilterByType SUBSTITUTE text/html Substitute "s|(.*+(.*){2222,}(.*)+(.*){22,})||iq" -cpu-exhaustion- Result: Long executing time, providing to memory exhaustion
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