Choosing a Message/Channel Identifier on a Public/Multicast Channel
Attack Pattern ID: 12 (Standard Attack Pattern Completeness: Complete)Typical Severity: HighStatus: Draft
+ Description


Attackers aware that more data is being fed into a multicast or public information distribution means can 'select' information bound only for another client, even if the distribution means itself forces users to authenticate in order to connect initally.

Doing so allows the attacker to gain access to possibly privileged information, possibly perpetrate other attacks through the distribution means by impersonation.

If the channel/message being manipulated is an input rather than output mechanism for the system, (such as a command bus), this style of attack could change its identifier from a less privileged to more so privileged channel or command.

Attack Execution Flow

  1. Determine the nature of messages being transported as well as the identifiers to be used as part of the attack

  2. If required, authenticate to the distribution channel

  3. If any particular client's information is available through the transport means simply by selecting a particular identifier, an attacker can simply provide that particular identifier.

  4. Attackers with client access connecting to output channels could change their channel identifier and see someone else's (perhaps more privileged) data.

+ Attack Prerequisites

Information and client-sensitive (and client-specific) data must be present through a distribution channel available to all users.

Distribution means must code (through channel, message identifiers, or convention) message destination in a manner visible within the distribution means itself (such as a control channel) or in the messages themselves.

+ Typical Likelihood of Exploit

Likelihood: Very High

+ Examples-Instances


A certain B2B interface on a large application codes for messages passed over a MQSeries queue, on a single "Partners" channel. Messages on that channel code for their client destination based on a partner_ID field, held by each message. That field is a simple integer. Attackers having access to that channel, perhaps a particularly nosey partner, can simply choose to store messages of another parnter's ID and read them as they desire. Note that authentication does not prevent a partner from leveraging this attack on other partners. It simply disallows Attackers without partner status from conducting this attack.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

All the attacker needs to discover is the format of the messages on the channel/distribution means and the particular identifier used within the messages.

+ Resources Required

The Attacker needs the ability to control source code or application configuration responsible for selecting which message/channel id is absorbed from the public distribution means.

+ Probing Techniques

Assisted protocol analysis: because the protocol under attack is a public channel, or one in which the attacker likely has authorized access to, they need simply to decode the aspect of channel or message interpretation that codes for message identifiers.

Probing is as simple as changing this value and watching its effect.

+ Solutions and Mitigations

Associate some ACL (in the form of a token) with an authenticated user which they provide middleware. The middleware uses this token as part of its channel/message selection for that client, or part of a discerning authorization decision for privileged channels/messages.

The purpose is to architect the system in a way that associates proper authentication/authorization with each channel/message.

Rearchitect system input/output channels as appropriate to distribute self-protecting data. That is, encrypt (or otherwise protect) channels/messages so that only authorized readers can see them.

+ Attack Motivation-Consequences
  • Information Leakage
  • Privilege Escalation
+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
201Information Leak Through Sent DataTargeted
306Missing Authentication for Critical FunctionSecondary
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
PeerOfAttack PatternAttack Pattern21Exploitation of Session Variables, Resource IDs and other Trusted Credentials 
Mechanism of Attack1000
ChildOfCategoryCategory216Abuse of Communication Channels 
Mechanism of Attack (primary)1000
+ Related Security Principles
  • Complete Mediation

+ Related Guidelines
  • Use Authentication Mechanisms, Where Appropriate, Correctly

  • Use Authorization Mechanisms Correctly: this refers to Ambiguity of authentication. Many authorization systems use ambiguous symbols (i.e., principal names) to identify principals allowing circumvention of authorization by using a different, though equivalent, principal name. For example, there are many implementations for restricting remote host access to local services that may allow many proper—but apparently different—names for unique hosts (e.g., fully qualified domain names, shortened names, CNAMEs, IPv4 addresses, IPv6 addresses).

+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: MediumIntegrity Impact: LowAvailability Impact: Low
+ Technical Context
Architectural Paradigms
+ Content History
John StevenCigital, Inc2007-02-10Initial core pattern content
Chiradeep B. ChhayaCigital, Inc2007-02-23Fleshed out pattern with extra content
Richard StruseVOXEM, Inc2007-03-26Review and feedback leading to changes in Description and Related Attack Patterns
Sean BarnumCigital, Inc2007-04-13Modified pattern content according to review and feedback