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CAPEC-182: Flash Injection

Attack Pattern ID: 182
Abstraction: Standard
Status: Draft
Presentation Filter:
+ Description
An attacker tricks a victim to execute malicious flash content that executes commands or makes flash calls specified by the attacker. One example of this attack is cross-site flashing, an attacker controlled parameter to a reference call loads from content specified by the attacker.
+ Likelihood Of Attack

High

+ Typical Severity

Medium

+ Relationships

The table(s) below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.

+ Relevant to the view "Mechanisms of Attack" (CAPEC-1000)
NatureTypeIDName
ChildOfMeta Attack PatternMeta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.137Parameter Injection
ParentOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.178Cross-Site Flashing
CanAlsoBeMeta Attack PatternMeta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.248Command Injection
+ Execution Flow
Explore
  1. Find Injection Entry Points: The attacker first takes an inventory of the entry points of the application. Spider the website for all available URLs that reference a Flash application. List all uninitialized global variables (such as _root.*, _global.*, _level0.*) in ActionScript, registered global variables in included files, load variables to external movies.

    Techniques
    Spider the website for all available URLs that reference a Flash application.
    List all uninitialized global variables (such as _root.*, _global.*, _level0.*) in ActionScript, registered global variables in included files, load variables to external movies.
Experiment
  1. Determine the application's susceptibility to Flash injection: Determine the application's susceptibility to Flash injection. For each URL identified in the explore phase, the attacker attempts to use various techniques such as direct load asfunction, controlled evil page/host, Flash HTML injection, and DOM injection to determine whether the application is susceptible to Flash injection. Test the page using direct load asfunction, getURL,javascript:gotRoot("")///d.jpg Test the page using controlled evil page/host, http://example.com/evil.swf Test the page using Flash HTML injection, "'><img src='asfunction:getURL,javascript:gotRoot("")//.jpg' > Test the page using DOM injection, (gotRoot(''))

    Techniques
    Test the page using direct load asfunction, getURL,javascript:gotRoot("")///d.jpg
    Test the page using controlled evil page/host, http://example.com/evil.swf
    Test the page using Flash HTML injection, "'><img src='asfunction:getURL,javascript:gotRoot("")//.jpg' >
    Test the page using DOM injection, (gotRoot(''))
Exploit
  1. Inject malicious content into target: Inject malicious content into target utilizing vulnerable injection vectors identified in the Experiment phase

+ Prerequisites
The target must be capable of running Flash applications. In some cases, the victim must follow an attacker-supplied link.
+ Skills Required
[Level: Medium]
The attacker needs to have knowledge of Flash, especially how to insert content the executes commands.
+ Resources Required
None: No specialized resources are required to execute this type of attack. The attacker may need to be able to serve the injected Flash content.
+ Consequences

The table below specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Confidentiality
Other
Integrity
Modify Data
Confidentiality
Read Data
Integrity
Modify Data
Confidentiality
Read Data
Integrity
Modify Data
Confidentiality
Read Data
Authorization
Execute Unauthorized Commands
Accountability
Authentication
Authorization
Non-Repudiation
Gain Privileges
Access Control
Authorization
Bypass Protection Mechanism
+ Mitigations
Implementation: remove sensitive information such as user name and password in the SWF file.
Implementation: use validation on both client and server side.
Implementation: remove debug information.
Implementation: use SSL when loading external data
Implementation: use crossdomain.xml file to allow the application domain to load stuff or the SWF file called by other domain.
+ Example Instances

In the following example, the SWF file contains

getURL('javascript:SomeFunc("someValue")','','GET')

A request like

http://example.com/noundef.swf?a=0:0;alert('XSS')

becomes

javascript:SomeFunc("someValue")?a=0:0;alert(123)
+ References
[REF-46] Stefano Di Paola. "Finding Vulnerabilities in Flash Applications". OWASP Appsec 2007. 2007-11-15.
[REF-47] Rudra K. Sinha Roy. "A Lazy Pen Tester's Guide to Testing Flash Applications". iViz. <http://www.ivizsecurity.com/blog/web-application-security/testing-flash-applications-pen-tester-guide/>.
[REF-48] Peleus Uhley. "Creating More Secure SWF Web Application". Adobe Systems Incorporated. <http://www.adobe.com/devnet/flashplayer/articles/secure_swf_apps.html>.
+ Content History
Submissions
Submission DateSubmitterOrganization
2014-06-23CAPEC Content TeamThe MITRE Corporation
Modifications
Modification DateModifierOrganization
2017-05-01CAPEC Content TeamThe MITRE Corporation
Updated Related_Attack_Patterns
2017-08-04CAPEC Content TeamThe MITRE Corporation
Updated Resources_Required
2018-07-31CAPEC Content TeamThe MITRE Corporation
Updated Attacker_Skills_or_Knowledge_Required

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Page Last Updated or Reviewed: July 31, 2018