Rule: 

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Sid: 
3541

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Summary:
This event is generated when RADIUS packets with specially crafted
Airlink records intended to cause a Denial of Service in Ethereal are
detected.

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Impact: 
Serious. Possible Denial of Service (DoS). Execution of arbitrary code
may also be possible.

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Detailed Information:
Ethereal is a multi-platform network protocol analyser capable of
displaying network data to the user in a graphical user interface.

Malicious packets, which arrive via UDP port 699, must meet a detailed
set of criteria to exploit this vulnerability. The requirements are:

 * Begin with a valid packet type of 0x01 (Registration Request), 0x03
 (Registration Reply), 0x14 (Registration Update), 0x15 (Registration
 Ack), 0x16 (Session Update), or 0x17 (Session Update Ack).
 * Have an extension type of 0x25 (Critical Vendor/Organization Specific
 Extension (OLD)) or 0x26 (Critical Vendor/Organization Specific Extension).
 * Have an application type of 0x0101 (Accounting (RADIUS)).
 * For the non-vendor specific rules, have an Airlink type of 0x1F.
 * For the vendor-specific rules, have an Airlink type of 0x1A, a
 sub-type of 0x0000159F ("3rd Generation Partnership Project 2
 (3GPP2)"), and contain string data (specified by 0x0A or 0x34 directly
 following the sub-type field).
 * Have a length of 31 or greater for the Airlink record, with 31 bytes
 actually being present.

Packets which are crafted to meet all of these criteria will overflow a
buffer, and arbitrary code may be injected for execution with the
privileges of the user running Ethereal.

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Affected Systems:
	Ethereal 0.10.9 and below

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Attack Scenarios: 
An attacker could send a crafted packet to a network Ethereal is
sniffing, or entice their victim to read a packet capture which contains
a malicious packet.

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Ease of Attack: 
Simple, as two exploits exist for the non-vendor specific overflow.

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False Positives:
None Known.

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False Negatives:
Packets may contain multiple extensions and/or Airlink records, and if
the malicious data is contained in the 2nd - Nth record, it will not be
detected by this rule.

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Corrective Action: 
Upgrade to the latest non-affected version of the software.

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Contributors: 
Alex Kirk <alex.kirk@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

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