CVE-2021-41773 path traversal case study for Apache HTTP Server

[CharanAnishK]

Case Study on Path Traversal in Apache HTTP Server (CVE-2021-41773):

This case study examines a vulnerability of critical path traversal in Apache HTTP Server 2.4.49 that enabled the unauthenticated attacker to gain access to arbitrary files by using percent-encoded directory traversal hints. The paper discusses the vulnerable code of server/core.c, shows real-world exploitation of the vulnerable code, the Apache multi-layers solution, and systematic prevention measures such as the correct use of canonicalization ordering, defense in depth implementation and automated security testing.

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Automated Analysis Results of This Use Case

Thank you for providing your use case! Apologies for the form letter, but it's a pleasure to see y'all :)

With technical knowledge work such as this project, it is important to structure information as well as possible, so that it can be processed automatically.

We also want to validate our inputs ;-)

So, this report contains the results of an automated analysis of the provided use case, looking for consistency with the documented format as covered in Section 3 "Case Study Structure" of the Style Guide.

Disclaimers:

• David Wheeler may provide guidance on how to handle these reports. We're grateful that you've put in this work already, and we don't want to burden you unnecessarily 'cuz you're probably busy :)
• Our style guide was not always 100% clear (as often happens early in technical knowledge work), so this analysis attempts to automatically resolve potential inconsistencies.
• This report is provided as a convenience. There may be some errors or omissions in this report.
• We will conduct deeper analysis at a later time.

Items are prioritized from Informative, Low, Medium, to High in terms of current importance to the project.

Analyzing Presence of Markdown

Markdown detected in the document.

Parser Issues

The following issues were encountered by the parser used to analyze this file. This might explain potential errors and false positives in the subsequent analysis.

• [Info] Guessing that line 7 contains a new section 'Introduction'
• [Info] Guessing that line 9 contains a new section 'Software'
• [Info] Guessing that line 13 contains a new section 'Weakness'
• [Info] Guessing that line 22 contains a new section 'Vulnerability'
• [Info] Guessing that line 45 contains a new section 'Exploit'
• [Info] Guessing that line 62 contains a new section 'Fix'
• [Info] Guessing that line 85 contains a new section 'Prevention'
• [Info] Guessing that line 104 contains a new section 'Fix'
• [Info] Guessing that line 166 contains a new section 'Prevention'
• [Info] Guessing that line 280 contains a new section 'Conclusion'
• [Info] Guessing that line 284 contains a new section 'References'
• [Info] Guessing that line 306 contains a new section 'Contributions'

Section Analysis

• [Med] Unexpected/non-standard section name: 'canonical path security check NOW perform security checks on canonical path' (this may break analysis)
• [High] Expected section name missing: 'Title'
  • Important: detailed analysis not performed for this missing section
• [High] 1 major section-name issues detected.
• [Med] Section 'Introduction' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Software' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Weakness' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Vulnerability' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Exploit' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Fix' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Prevention' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Fix' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Prevention' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Conclusion' is expected to have 3 hash marks, but it has 0
• [Med] Section 'References' is expected to have 3 hash marks, but it has 0
• [Med] Section 'Contributions' is expected to have 3 hash marks, but it has 0

Analyzing Introduction Section

No issues found.

Analyzing Software Section

• [High] Missing **Name:** in Software section
• [High] Missing **Language:** in Software section
• [High] Missing **URL:** in Software section

Analyzing Weakness Section

No issues found.

Analyzing Vulnerability Section

• [Med] Vulnerability section does not appear to contain a 'vulnerable file:' label
• [Med] No apparent source code ``` tags in Vulnerability section

Analyzing Fix Section

• [Med] No apparent source code ``` tags in Fix section

Analyzing Fix Section

• [Med] Fix section does not appear to contain a 'fixed file:' label
• [Med] No apparent source code ``` tags in Fix section

Analyzing References Section

No issues found.