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Okapi protects all modules where it proxies requests to (the mod-* modules) from the denial-of-service attack of CVE-2021-45105 (infinite recursion in MDC lookup evaluation) by filtering malicious values in the fields used for MDC (OKAPI-1058), therefore those modules don't need log4j >= 2.17.0 and can safely continue to use log4j 2.16.0.
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Many back-end modules are affected by the Log4Shell issue, until new jar files and new docker containers with a fixed version are ready the existing back-end modules should be reconfigured with an environment variable that disables the flaw for most cases in log4j:
LOG4J_FORMAT_MSG_NO_LOOKUPS=true- Append
-Dlog4j2.formatMsgNoLookups=trueto theJAVA_OPTIONSvariable
Pick one of the two options.
Example for the second option: If the existing configuration has JAVA_OPTIONS="-XX:MaxRAMPercentage=66.0" then the new configuration should beJAVA_OPTIONS="-XX:MaxRAMPercentage=66.0 -Dlog4j2.formatMsgNoLookups=true"
SQL query to do this, posted by Lucy Menon on #sys-ops Slack channel, assuming that all modules in use already have a JAVA_OPTIONS env entry:
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Not completely. It only limits exposure while leaving some attack vectors open. Using the configuration variables is a temporary measure for the time until patched FOLIO modules are available. Please upgrade to patched modules as soon as possible.
From: https://logging.apache.org/log4j/2.x/security.html
History
Older (discredited) mitigation measures
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Modules that use a vulnerable log4j version must be upgraded to >= 2.17.0, however, mod-* modules that already have upgraded to 2.16.0 don't need to upgrade to 2.17.0. Okapi protects all modules where it proxies requests to from the denial-of-service attack of CVE-2021-45105 (infinite recursion in MDC lookup evaluation) by filtering malicious values in the fields used for MDC (OKAPI-1058), therefore those modules don't need log4j 2.17.0 and can safely continue to use log4j 2.16.0.
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No, updating to log4j >= 2.16.0 is sufficient. LOG4J_FORMAT_MSG_NO_LOOKUPS=true or -Dlog4j2.formatMsgNoLookups=true should only be used by sysops for unpatched modules as a temporary fix. Don't add them to the ModuleDescriptors or LaunchDescriptors a module ships with. For details see section "Is using configuration variables secure?" above.
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