Web Logs Tampering |
| Attack Pattern ID: 81 (Standard Attack Pattern Completeness: Complete) | Typical Severity: High | Status: Draft |
DescriptionSummary
Web Logs Tampering attacks involve an attacker injecting, deleting or otherwise tampering with the contents of web logs typically for the purposes of masking other malicious behavior. Additionally, writing malicious data to log files may target jobs, filters, reports, and other agents that process the logs in an asynchronous attack pattern. This pattern of attack is similar to "Log Injection-Tampering-Forging" except that in this case, the attack is targeting the logs of the web server and not the application.
Attack Execution Flow
Determine Application Web Server Log File Format:
The attacker observes the system and looks for indicators of which logging utility is being used by the web server.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Determine logging utility being used by application web server (e.g. log4j), only possible if the application is known by the attacker or if the application returns error messages with logging utility information.
env-WebOutcomes
ID type Outcome Description 1 Success Attacker determines log file format used by application web server.2 Inconclusive Attacker cannot conclusively determine log file format; he/she can only guess what the format is.
Determine Injectable Content:
The attacker launches various logged actions with malicious data to determine what sort of log injection is possible.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Attacker triggers logged actions with maliciously crafted data as inputs, parameters, arguments, etc.
env-WebOutcomes
ID type Outcome Description 1 Success Attacker observes content successfully injected into web logs.2 Inconclusive Attacker lacks capability to observe if content was successfully injected into web logs.
Manipulate Log Files:
The attacker alters the log contents either directly through manipulation or forging or indirectly through injection of specially crafted request that the web server will receive and write into the logs. This type of attack typically follows another attack and is used to try to cover the traces of the previous attack.
Attack Step Techniques
ID Attack Step Technique Description Environments 1 Indirectly through injection, use carriage return and/or line feed characters to start a new line in the log file, and then, add a fake entry.
For example: The HTTP request for "/index.html%0A%0DIP_ADDRESS- - DATE_FORMAT] "GET /forged-path HTTP/1.1" 200 - "-" USER_AGENT" may add the log line into Apache "access_log" (for example). Different applications may require different encodings of the carriage return and line feed characters.
env-Web2 Directly through log file or database manipulation, use carriage return and/or line feed characters to start a new line in the log file, and then, add a fake entry.
For example: The HTTP request for "/index.html%0A%0DIP_ADDRESS- - DATE_FORMAT] "GET /forged-path HTTP/1.1" 200 - "-" USER_AGENT" may add the log line into Apache "access_log" (for example). Different applications may require different encodings of the carriage return and line feed characters.
env-Web3 Directly through log file or database manipulation, modify existing log entries.
env-WebOutcomes
ID type Outcome Description 1 Success Forged entry or other malicious data inserted into application's logs.2 Failure No entry inserted into logs, or the entry is visibly distinguishable from real entries.Security Controls
ID type Security Control Description 1 Preventative Input validation to ensure that only legal characters supplied by users can be entered into log files2 Preventative Encode information from user such that any unexpected characters are encoded safely before they are entered into log files.3 Preventative Post-processing of log files to remove or encode dangerous characters before displaying to a user may help in some cases. It will not help remove fake log entries entered using carriage return and line feed characters, however.
Attack PrerequisitesTarget server software must be a HTTP server that performs web logging.
Typical Likelihood of ExploitLikelihood: Medium
Methods of Attack- Modification of Resources
- Time and State
Examples-InstancesDescription
Most web servers have a public interface, even if the majority of the site is password protected, there is usually at least a login site and brochureware that is publicly available. HTTP requests to the site are also generally logged to a Web log. From an attacker point of view, standard HTTP requests containing a malicious payload can be sent to the public website (with no other access required), when those requests appear in the log (such as http://victimsite/index.html?< malicious script> if they are followed by an administrator this may be sufficient to probe the administrator's host or local network.
Attacker Skills or Knowledge RequiredSkill or Knowledge Level: Low
To input faked entries into Web logs
Resources RequiredAbility to send specially formatted HTTP request to web server
Solutions and MitigationsDesign: Use input validation before writing to web log
Design: Validate all log data before it is output
Attack Motivation-Consequences- Data Modification
Injection VectorForged log entry delivered through HTTP Request.
PayloadHTTP request
Activation ZoneWeb log, log reporting systems
Payload Activation ImpactLog data contains data designed to trick administrators and auditors as to chain of events. Limit ability to conduct forensics and other investigations/responses.
Related Weaknesses| CWE-ID | Weakness Name | Weakness Relationship Type |
|---|---|---|
| 117 | Improper Output Sanitization for Logs | Targeted |
| 93 | Failure to Sanitize CRLF Sequences ('CRLF Injection') | Targeted |
| 92 | DEPRECATED: Improper Sanitization of Custom Special Characters | Targeted |
| 221 | Information Loss or Omission | Targeted |
| 96 | Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection') | Secondary |
| 20 | Improper Input Validation | Secondary |
| 150 | Improper Neutralization of Escape, Meta, or Control Sequences | Secondary |
| 276 | Incorrect Default Permissions | Targeted |
| 279 | Incorrect Execution-Assigned Permissions | Secondary |
| 116 | Improper Encoding or Escaping of Output | Secondary |
| 713 | OWASP Top Ten 2007 Category A2 - Injection Flaws | Targeted |
Related Attack Patterns| Nature | Type | ID | Name | Description | View(s) this relationship pertains to |
|---|---|---|---|---|---|
| ChildOf |  Attack Pattern | 268 | Audit Log Manipulation | Mechanism of Attack (primary)1000 |
Purposes- Obfuscation
CIA Impact Technical Context| Architectural Paradigms | Client-Server SOA |
|---|---|
| Frameworks | All |
| Platforms | All |
| Languages | All |
References Content History| Submissions | ||||
|---|---|---|---|---|
| Submitter | Organization | Date | ||
| G. Hoglund and G. McGraw. Exploiting Software: How to Break Code. Addison-Wesley, February 2004. | Cigital, Inc | 2007-01-01 | ||
| Modifications | |||||
|---|---|---|---|---|---|
| Modifier | Organization | Date | Comments | ||
| Gunnar Peterson | Cigital, Inc | 2007-02-28 | Fleshed out content to CAPEC schema from the original descriptions in "Exploiting Software" | ||
| Sean Barnum | Cigital, Inc | 2007-03-09 | Review and revise | ||
| Romain Gaucher | Cigital, Inc | 2009-02-10 | Created draft content for detailed description | ||
| Sean Barnum | Cigital Federal, Inc | 2009-04-13 | Reviewed and revised content for detailed description | ||
