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IBM WebSphere

TMA-WEBSPHERE-4.3.1

Ensure 'signatureAlgorithm' asymmetric key algorithm is set for encrypting the JSON Web Tokens

HighLevel 1Automatedwebsphere

Description

The signatureAlgorithm is used to sign the JWT and can be configured to use different algorithms like HS256 (symmetric), RS256 (asymmetric). Audit: reads server.xml, configDropins/defaults/*.xml, configDropins/overrides/*.xml and files pulled in with <include> for every Liberty server found under WLP_USER_DIR, /opt/ibm/wlp/usr, /opt/IBM/WebSphere/Liberty/usr, /opt/ol/wlp/usr, /usr/local/wlp/usr or /config; it ignores XML comments and fails if no server.xml is readable. <openidConnectProvider> signatureAlgorithm must be an asymmetric algorithm such as RS256 (default HS256). The openidConnectClient element is covered by 4.3.6. Passes when no <openidConnectProvider> element is configured (feature not in use). The attribute must be set explicitly because the Liberty default is not compliant.

How it is checked

Audit method: Shell command

shell
bad=0; n=0; nl='
'
r=""
for b in "${WLP_USER_DIR:-}" /opt/ibm/wlp/usr /opt/IBM/WebSphere/Liberty/usr /opt/ol/wlp/usr /usr/local/wlp/usr; do
  [ -n "$b" ] && [ -d "$b/servers" ] || continue
  for s in "$b"/servers/*/; do [ -f "${s}server.xml" ] && r="$r$s$nl"; done
done
[ -f /config/server.xml ] && r="$r/config/$nl"
strip(){ awk 'BEGIN{RS="<!--"} NR==1{printf "%s",$0; next} {i=index($0,"-->"); if(i) printf "%s",substr($0,i+3)}'; }
gather(){ s=$1; { cat "${s}server.xml" "${s}"configDropins/defaults/*.xml "${s}"configDropins/overrides/*.xml; } 2>/dev/null | strip
  for loc in $(cat "${s}server.xml" "${s}"configDropins/defaults/*.xml "${s}"configDropins/overrides/*.xml 2>/dev/null | strip | tr '\r\n\t' '   ' | grep -oE '<include[[:space:]][^>]*>' | sed -n 's/.*location[[:space:]]*=[[:space:]]*"\([^"]*\)".*/\1/p'); do
    case $loc in http*) continue;; esac; loc=$(printf '%s' "$loc" | sed "s#\${server.config.dir}/*##"); case $loc in /*) f=$loc;; *) f=$s$loc;; esac
    [ -f "$f" ] && strip < "$f"; done; }
tag(){ printf '%s\n' "$X" | grep -oE "<$1([[:space:]][^>]*)?>"; }
chk(){ t=$(tag "$1"); if [ -z "$t" ]; then [ "$5" = na ] && return 0; [ "$4" = y ] && return 0; return 1; fi
  tot=$(printf '%s\n' "$t" | grep -c ''); v=$(printf '%s\n' "$t" | sed -n "s/.*[[:space:]]$2[[:space:]]*=[[:space:]]*[\"']\([^\"']*\)[\"'].*/\1/p"); st=0
  [ -n "$v" ] && st=$(printf '%s\n' "$v" | grep -c ''); case " config httpSession webAppSecurity jwtSso webContainer httpDispatcher applicationMonitor sslDefault httpOptions ltpa mpMetrics samesite transportLayer authenticationLayer attributeLayer " in *" $1 "*) [ "$st" -gt 0 ] && tot=$st;; esac; ok=$3; neg=n; case $ok in '!'*) neg=y; ok=${ok#!};; esac
  if [ "$st" -gt 0 ]; then m=$(printf '%s\n' "$v" | grep -ciE "^($ok)\$"); if [ "$neg" = n ]; then [ "$m" -eq "$st" ] || return 1; else [ "$m" -eq 0 ] || return 1; fi; fi
  [ "$st" -lt "$tot" ] && [ "$4" != y ] && return 1; return 0; }
IFS="$nl"; for s in $r; do n=$((n+1)); X=$(gather "$s" | tr '\r\n\t' '   ' | tr -s ' ')
chk openidConnectProvider signatureAlgorithm '(RS|ES|PS)(256|384|512)' n na || bad=1
done; unset IFS; [ "$n" -gt 0 ] || exit 1; [ "$bad" -eq 0 ] && echo compliant || echo noncompliant
Expected output
compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Add the signatureAlgorithm attribute to the openidConnectProvider element and set it to a strong algorithm, such as RS256 in ${server.config.dir}/configDropins/overrides/*.xml. <openidConnectProvider signatureAlgorithm="RS256" /> <openidConnectClient signatureAlgorithm="RS256" />

Properties

Operating systems
Any
Tags
websphereoidcjwt
Reference
CIS IBM WebSphere Liberty Benchmark v1.0.0 - 4.3.1 Ensure 'signatureAlgorithm' asymmetric key algorithm is set for encrypting the JSON Web Tokens

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell
tmaegis scan --target websphere