User-Controlled Filename
Attack Pattern ID: 73 (Standard Attack Pattern Completeness: Complete)Typical Severity: HighStatus: Draft
+ Description


An attack of this type involves an attacker inserting malicious characters (such as a XSS redirection) into a filename, directly or indirectly that is then used by the target software to generate HTML text or other potentially executable content. Many websites rely on user-generated content and dynamically build resources like files, filenames, and URL links directly from user supplied data. In this attack pattern, the attacker uploads code that can execute in the client browser and/or redirect the client browser to a site that the attacker owns. All XSS attack payload variants can be used to pass and exploit these vulnerabilities.

+ Attack Prerequisites

The victim must trust the name and locale of user controlled filenames.

+ Typical Likelihood of Exploit

Likelihood: High

+ Methods of Attack
  • Modification of Resources
+ Examples-Instances


Phishing attacks rely on a user clicking on links on that are supplied to them by attackers masquerading as a trusted resource such as a bank or online auction site. The end user's email client hosts the supplid resource name in this case via email. The resource name, however may either 1) direct the client browser to a malicious site to steal credentical and/or 2) execute code on the client machine to probe the victim's host system and network environment.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

To achieve a redirection and use of less trusted source, an attacker can simply edit data that the host uses to build the filename

Skill or Knowledge Level: Medium

Deploying a malicious "look a like" site (such as a site masquerading as a bank or online auction site) that the user enters their authentication data into.

Skill or Knowledge Level: High

Exploiting a client side vulnerability to inject malicious scripts into the browser's executable process.

+ Solutions and Mitigations

Design: Use browser technologies that do not allow client side scripting.

Implementation: Ensure all content that is delivered to client is sanitized against an acceptable content specification.

Implementation: Perform input validation for all remote content.

Implementation: Perform output validation for all remote content.

Implementation: Disable scripting languages such as Javascript in browser

Implementation: Scan dynamically generated content against validation specification

+ Attack Motivation-Consequences
  • Privilege Escalation
  • Run Arbitrary Code
  • Denial of Service
  • Information Leakage
+ Injection Vector

Payload delivered through user controlled filename.

+ Payload

Command(s) executed directly on host

+ Activation Zone

Client machine and client network

+ Payload Activation Impact

Enables attacker to execute server side code with any commands that the program owner has privileges to.

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
20Improper Input ValidationTargeted
184Incomplete BlacklistSecondary
96Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection')Targeted
348Use of Less Trusted SourceTargeted
116Improper Encoding or Escaping of OutputTargeted
350Improperly Trusted Reverse DNSTargeted
86Improper Neutralization of Invalid Characters in Identifiers in Web PagesSecondary
697Insufficient ComparisonTargeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern63Simple Script Injection 
Mechanism of Attack1000
ChildOfAttack PatternAttack Pattern165File Manipulation 
Mechanism of Attack (primary)1000
+ Purposes
  • Penetration
  • Exploitation
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: HighAvailability Impact: High
+ 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
Richard StruseVOXEM, Inc2007-03-26Review and feedback leading to changes in Related Attack Patterns
Sean BarnumCigital, Inc2007-04-13Modified pattern content according to review and feedback