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https://issues.apache.org/jira/browse/JAMES-3829?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benoit Tellier closed JAMES-3829.
---------------------------------
    Fix Version/s: 3.8.0
       Resolution: Fixed

Now user should adapt their code in order to serialize their payloads as bytes 
by themselves.

> Mailet API: drop Serializable entirely
> --------------------------------------
>
>                 Key: JAMES-3829
>                 URL: https://issues.apache.org/jira/browse/JAMES-3829
>             Project: James Server
>          Issue Type: Improvement
>          Components: Mailet Contributions
>            Reporter: Benoit Tellier
>            Priority: Major
>             Fix For: 3.8.0
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> h3. Why ?
> Deserialization attacks is a great classic. An attacker can feed crafted data 
> into your deserialization process to execute (given vulnerable class on the 
> classpath) arbitrary code.
> Latest exemple: https://security.snyk.io/vuln/SNYK-JAVA-ORGSCALALANG-3032987
> The problem is that the description of "what" is encoded in the payload, and 
> blindly followed by the deserializer. Such a genericity comes at a security 
> risk.
> Several strategies of defense can be followed:
>  - Avoid deserialization, only deserialize to a restrictive, safe, set of 
> class.
>  - Fix all libraries allowing deserialization related exploit. Which leaves 
> exposed to new findings, and can be thought of a cat-and-mouse race.
> We use serialization in a couple of place:
>  - JMX CLI that an administrator can turn off
>  - The mailet-api allows attribute serialisation. TThis is done through the 
> means of the FST serializer that can be used to deserialize any class on the 
> classpath and will execute its constructor (I tried!)
> There is no way to turn off FST deserialization.
> The associated surface is limited: an attacker need to be able to craft DB or 
> brokers payload: such an access would already be a major threat in itself!
> Yet having uncontrolled serialization in a system as conplex as James leaves 
> me thinking... What iff attributeValue serialization is exposed in places I 
> did not expect? 
> It's also worth mentionning that FST itself is not active for other a year - 
> not what I want for security sensitive code.
> Thus I would rather restrict the feature here as by design this would make us 
> vulnerable.
> h3. How ?
> Remove completly FST.
> Explain that the user is expected to serialize / deserialize his payloads 
> himself.
> Introduce also a way to have "compute only" attributes, with a serializer 
> that drops the attribute.
> h3. Inventory
> The following use cases uses FST serialization:
>  - Calendar: use a compute only serializer as this is used to cary info 
> between 2 mailets.
>  - SMIME: put certificates as bytes
>  - ProcessorUtil mailet error: use a compute only serializer
>  - ActionUtils mailAddress: use a string representation
> h3. Migration
> Recode the FST serializer so that it does nothing. THis way, emails having 
> some FST serialized attributes will still be readable.



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