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From "bruce liu (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (WW-4146) cache attack at OgnlUtil.expressions
Date Wed, 24 Jul 2013 15:11:50 GMT

    [ https://issues.apache.org/jira/browse/WW-4146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13718454#comment-13718454
] 

bruce liu edited comment on WW-4146 at 7/24/13 3:10 PM:
--------------------------------------------------------

i don't agree that it will reverse the whole architecture of Struts and let appliaction firewall
to solve problem .

maybe i am simple, but here is my simple idea :

i add an field in class ParametersInterceptor:
private static ConcurrentHashMap<Class, Set<String>> properyCache = new ConcurrentHashMap<Class,
Set<String>>();

in method setParameters, i will replace that loop like below :

Class actionClass = action.getClass();
Map<String, Expression> propertySet = properyCache.get(actionClass);
if(propertySet == null) {
	synchronized(actionClass) {
		propertySet = new HashSet<String>();
		// reflect actionClass and put properties into an set propertySet .
	}
}

for (Map.Entry<String, Object> entry : acceptableParameters.entrySet()) {
	String name = entry.getKey();
	Object value = entry.getValue();
	if (propertySet.contains(name)) {
	// maybe we should use other check strategy not contains method to deal with expression like
user.address
		try {
			newStack.setParameter(name, value);
		} catch (RuntimeException e) {
			// some code do log here, i ignore it .
		}
	}
}

i think it may work and needn't to change much .

as long as there is a cache and user can control what will be cached , no matter what container
you use, it will be a hidden trouble .

                
      was (Author: coderbee):
    i don't agree that it will reverse the whole architecture of Struts and let appliaction
firewall to solve problem .

maybe i am simple, but here is my simple idea :

i add an field in class ParametersInterceptor:
private static ConcurrentHashMap<Class, Set<String>> properyCache = new ConcurrentHashMap<Class,
Set<String>>();

in method setParameters, i will replace that loop like below :

Class actionClass = action.getClass();
Map<String, Expression> propertySet = properyCache.get(actionClass);
if(propertySet == null) {
	synchronized(actionClass) {
		propertySet = new HashSet<String>();
		// reflect actionClass and put properties into an set propertySet .
	}
}

for (Map.Entry<String, Object> entry : acceptableParameters.entrySet()) {
	String name = entry.getKey();
	Object value = entry.getValue();
	if (propertySet.contains(name)) {
	// maybe we should use other check strategy not contains method to deal with expression like
user.address
		try {
			newStack.setParameter(name, value);
		} catch (RuntimeException e) {
			// some code do log here, i ignore it .
		}
	}
}

i think it may work and needn't to change much .

as long as there is a cache and use can control what will be cached , no matter what container
you use, it will be a hidden trouble .

                  
> cache attack at  OgnlUtil.expressions
> -------------------------------------
>
>                 Key: WW-4146
>                 URL: https://issues.apache.org/jira/browse/WW-4146
>             Project: Struts 2
>          Issue Type: Bug
>          Components: Expression Language
>    Affects Versions: 2.3.15.1
>            Reporter: bruce liu
>             Fix For: 2.3.17
>
>
> in class com.opensymphony.xwork2.ognl.OgnlUtil, code :
> {code:java}
> tree = expressions.get(expression);
> if (tree == null) {
> 	tree = Ognl.parseExpression(expression);
> 	expressions.putIfAbsent(expression, tree);
> }
> {code}
> every parameter in the request cached in  field expressions  which is an instances of
ConcurrentMap<String, Object>, use parameterName as key. so i construct huge different
parameters that has different name (like  "abc[123],  abc[124]" ), they all cached in  expressions,
this cause outofmemory error, and let map acted like a list .

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