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From: Paul King <paulk@apache.org>
Date: Sat, 14 Jan 2017 22:23:37 +1000
Message-ID: <CADRx3PMZ2hBCGDTY35zYXFGaDnjAs0tc5-upaVs6QN2sYUejyA@mail.gmail.com>
Subject: [CVE-2016-6814] Apache Groovy Information Disclosure
To: dev@groovy.codehaus.org, security@apache.org, announce@apache.org,
	users@groovy.apache.org
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archived-at: Sat, 14 Jan 2017 12:23:40 -0000

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Severity: Important

Vendor: The Apache Software Foundation

Versions Affected:

* Unsupported Codehaus versions of Groovy from 1.7.0 to 2.4.3
* Apache Groovy 2.4.4 to 2.4.7
* Fixed in version 2.4.8

Impact:

Remote execution of untrusted code, DoS

Description:

When an application with Groovy on classpath uses standard
Java serialization mechanisms, e.g. to communicate between servers
or to store local data, it is possible for an attacker to bake a special
serialized object that will execute code directly when deserialized.
All applications which rely on serialization and do not isolate the
code which deserializes objects are subject to this vulnerability.
This is similar to CVE-2015-3253 but this exploit involves extra
wrapping of objects and catching of exceptions which are now safe
guarded against.

Mitigation:

Users of Groovy relying on (de)serialization with the affected versions
should apply one of the following mitigations:

* Isolate the code doing the (de)serialization
* Upgrade to Apache Groovy 2.4.8 or later
* Users of older versions of Groovy can apply the following patch to the
`MethodClosure` class
(`src/main/org/codehaus/groovy/runtime/MethodClosure.java`):

```
public class MethodClosure extends Closure {
+    private void readObject(java.io.ObjectInputStream stream) throws
IOException, ClassNotFoundException {
+        if (ALLOW_RESOLVE) {
+            stream.defaultReadObject();
+        }
+        throw new UnsupportedOperationException();
+    }
```

Credit:

This vulnerability was discovered by:

* Sam Thomas of Pentest Limited working with Trend Micro's Zero Day
Initiative

History:

* 2016-09-20 Original advisory
* 2017-01-12 Updated information on affected versions

References:

* http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-6814
* http://groovy-lang.org/security.html

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<div dir=3D"ltr"><div>Severity: Important</div><div><br></div><div>Vendor: =
The Apache Software Foundation</div><div><br></div><div>Versions Affected:<=
/div><div><br></div><div>* Unsupported Codehaus versions of Groovy from 1.7=
.0 to 2.4.3</div><div>* Apache Groovy 2.4.4 to 2.4.7</div><div>* Fixed in v=
ersion 2.4.8</div><div><br></div><div>Impact:</div><div><br></div><div>Remo=
te execution of untrusted code, DoS</div><div><br></div><div>Description:</=
div><div><br></div><div>When an application with Groovy on classpath uses s=
tandard</div><div>Java serialization mechanisms, e.g. to communicate betwee=
n servers</div><div>or to store local data, it is possible for an attacker =
to bake a special</div><div>serialized object that will execute code direct=
ly when deserialized.</div><div>All applications which rely on serializatio=
n and do not isolate the</div><div>code which deserializes objects are subj=
ect to this vulnerability.</div><div>This is similar to CVE-2015-3253 but t=
his exploit involves extra</div><div>wrapping of objects and catching of ex=
ceptions which are now safe</div><div>guarded against.</div><div><br></div>=
<div>Mitigation:</div><div><br></div><div>Users of Groovy relying on (de)se=
rialization with the affected versions</div><div>should apply one of the fo=
llowing mitigations:</div><div><br></div><div>* Isolate the code doing the =
(de)serialization</div><div>* Upgrade to Apache Groovy 2.4.8 or later</div>=
<div>* Users of older versions of Groovy can apply the following patch to t=
he</div><div>`MethodClosure` class (`src/main/org/codehaus/groovy/runtime/M=
ethodClosure.java`):</div><div><br></div><div>```</div><div>public class Me=
thodClosure extends Closure {</div><div>+ =C2=A0 =C2=A0private void readObj=
ect(java.io.ObjectInputStream stream) throws</div><div>IOException, ClassNo=
tFoundException {</div><div>+ =C2=A0 =C2=A0 =C2=A0 =C2=A0if (ALLOW_RESOLVE)=
 {</div><div>+ =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0stream.defaultReadO=
bject();</div><div>+ =C2=A0 =C2=A0 =C2=A0 =C2=A0}</div><div>+ =C2=A0 =C2=A0=
 =C2=A0 =C2=A0throw new UnsupportedOperationException();</div><div>+ =C2=A0=
 =C2=A0}</div><div>```</div><div><br></div><div>Credit:</div><div><br></div=
><div>This vulnerability was discovered by:</div><div><br></div><div>* Sam =
Thomas of Pentest Limited working with Trend Micro&#39;s Zero Day Initiativ=
e</div><div><br></div><div>History:</div><div><br></div><div>* 2016-09-20 O=
riginal advisory</div><div>* 2017-01-12 Updated information on affected ver=
sions</div><div><br></div><div>References:</div><div><br></div><div>* <a hr=
ef=3D"http://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2016-6814">http:/=
/cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2016-6814</a></div><div>* <a =
href=3D"http://groovy-lang.org/security.html">http://groovy-lang.org/securi=
ty.html</a></div><div><br></div></div>

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