GHSA-733v-p3h5-qpq7: GraphQL Armor Cost-Limit Plugin Bypass via Introspection Query Obfuscation

Summary

A query cost restriction using the cost-limit can be bypassed if ignoreIntrospection is enabled (which is the default configuration) by naming your query/fragment __schema.

Details

At the start of the computeComplexity function, we have the following check for ignoreIntrospection option:

if (this.config.ignoreIntrospection && 'name' in node && node.name?.value \=== '\_\_schema') {
  return 0;
}

However, the node can be FieldNode | FragmentDefinitionNode | InlineFragmentNode | OperationDefinitionNode | FragmentSpreadNode

So, for example, sending the following query

query hello { books { title } }

would create an OperationDefinitionNode with node.name.value == ‘hello’

The proper way to handle this would be to check for the __schema field, which would create a FieldNode.

The fix is

if (
  this.config.ignoreIntrospection &&
  'name' in node &&
  node.name?.value \=== '\_\_schema' &&
  node.kind \=== Kind.FIELD
) {
  return 0;
}

to assert that the node must be a FieldNode

PoC

query { …__schema }

fragment __schema on Query { books { title author } }

query __schema { books { title author } }

Impact

Applications using GraphQL Armor Cost Limit plugin with ignoreIntrospection enabled.

Fix:

Fixed on 772. A quick patch would be to set ignoreIntrospection to false.

References

• GHSA-733v-p3h5-qpq7
• Escape-Technologies/graphql-armor#772
• Escape-Technologies/graphql-armor@5a32954