Analog In-band Switching Signals (aka Blue Boxing)
Attack Pattern ID: 5 (Detailed Attack Pattern Completeness: Complete)Typical Severity: Very HighStatus: Draft
+ Description


This attack against older telephone switches and trunks has been around for decades. The signal is sent by the attacker to impersonate a supervisor signal. This has the effect of rerouting or usurping command of the line and call. While the US infrastructure proper may not contain widespread vulnerabilities to this type of attack, many companies are connected globally through call centers and business process outsourcing. These international systems may be operated in countries which have not upgraded telco infrastructure and so are vulnerable to Blue boxing.

Blue boxing is a result of failure on the part of the system to enforce strong authentication for administrative functions. While the infrastructure is different than standard current applications like web applications, there are hisotrical lessons to be learned to upgrade the access control for administrative functions.

+ Attack Prerequisites

System must use weak authentication mechanisms for administrative functions.

+ Typical Likelihood of Exploit

Likelihood: Medium

+ Methods of Attack
  • Injection
  • Protocol Manipulation
+ Examples-Instances


Attacker identifies a vulnerable CCITT-5 phone line, and sends a combination tone to the switch in order to request administrative access. Based on tone and timing parameters the request is verified for access to the switch. Once the attacker has gained control of the switch launching calls, routing calls, and a whole host of opportunities are available.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

Given a vulnerable phone system, the attacker's technical vector relies on attacks that are well documented in cracker 'zines and have been around for decades.

+ Resources Required

CCITT-5 or other vulnerable lines, with the ability to send tones such as combined 2,400 Hz and 2,600 Hz tones to the switch

+ Solutions and Mitigations

Implementation: Upgrade phone lines. Note this may be prohibitively expensive

Use strong access control such as two factor access control for adminsitrative access to the switch

+ Attack Motivation-Consequences
  • Denial of Service
  • Privilege Escalation
+ Injection Vector

Payload delivered through standard communication protocols.

+ Payload

Command(s) executed directly on host

+ Activation Zone

Client machine and client network

+ Payload Activation Impact

Enables calls to be rerouted.

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
264Permissions, Privileges, and Access ControlsTargeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfCategoryCategory152Injection (Injecting Control Plane content through the Data Plane) 
Mechanism of Attack (primary)1000
+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: LowIntegrity Impact: MediumAvailability Impact: Medium
+ Technical Context
Architectural Paradigms
+ References
G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.
+ Content History
G. Hoglund and G. McGraw. Exploiting Software: How to Break Code. Addison-Wesley, February 2004.Cigital, Inc2007-01-01
Gunnar PetersonCigital, Inc2007-02-28Fleshed out content to CAPEC schema from the original descriptions in "Exploiting Software"
Sean BarnumCigital, Inc2007-03-09Review and revise