Uncontrolled Resource Consumption with Highly-Compressed XMPP Stanzas

[Giancarlo Pellegrino <gpellegrino () cs tu-darmstadt de>]

Hi all,


Several XMPP server implementations that support application-layer 
compression (XEP-0138) suffer from an uncontrolled resource consumption 
vulnerability (CWE-400). This vulnerability can be remotely exploited by 
attackers to mount Denial-of-Service attacks by sending 
highly-compressed XML elements over XMPP streams.

Affected servers are reported to:

1. Consume the virtual memory; in certain cases, it has been reported 
that servers are terminated by the operating system for out of memory 
conditions;
2. Monopolize the use of the CPU;
3. In certain cases, not allow administrators to disable stream compression.

It is best to upgrade to corrected server code. An alternative, 
temporary workaround is to disable XMPP-level compression.

More details and the list of affected implementations can be found in 
the security notice published by the XMPP Standards Foundation:

http://xmpp.org/resources/security-notices/uncontrolled-resource-consumption-with-highly-compressed-xmpp-stanzas/


Thank you.

Best Regards,
Giancarlo Pellegrino

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