Case study on Simjacker - A telecom software vulnerability enabling remote device control.

[nchandansjce]

The Simjacker vulnerability (GHSA-mq4h-3x66-jfc7, GHSA-287m-gfcr-hmjw), a serious security flaw found in 2019 that affected SIM Toolkit (S@T Browser) software. It allowed attackers to send special binary SMS messages that could run commands on users' phones without them knowing. It revealed how weak security in SIM Toolkit (S@T Browser) software could let attackers remotely control mobile devices through hidden SMS commands. This case study aims to explain how it happened and what lessons developers can learn from it.

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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] Inferring that line 1 contains the title

Section Analysis

• [Info] 0 major section-name issues detected.
• [Med] Section 'Introduction' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Software' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Weakness' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Vulnerability' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Exploit' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Fix' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Prevention' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Conclusion' is expected to have 3 hash marks, but it has 2
• [Med] Section 'References' is expected to have 3 hash marks, but it has 2
• [Med] Section 'Contributions' is expected to have 3 hash marks, but it has 2

Analyzing Title Section

Note: the analysis may be incorrect depending on how
you provided the title. This an issue with the analyzer.

Inferred/Extracted Title begins with text: 'Simjacker - A telecom software vulnerability enabl...'

• [Low] Title does not contain only capital letters
• [Med] Title contains more than 8 words (longer than the recommended 4 to 6)

Analyzing Introduction Section

No issues found.

Analyzing Software Section

No issues found.

Analyzing Weakness Section

No issues found.

Analyzing Vulnerability Section

• [Med] Vulnerability section does not appear to contain a 'vulnerable file:' label

Analyzing Fix Section

• [Med] Fix section does not appear to contain a 'fixed file:' label

Analyzing References Section

No issues found.

[stevechristeycoley]

This is a brief checklist for review of this writeup for possible
inclusion in the Secure Coding Case Studies work.

Review Information

Metadata	Info
Author	Chandan Nanjundaswamy
Reviewer	Steve Christey Coley
Start Date	2025-12-19 16:53:00
End Date	2025-12-19 17:08:00
PR	#36
PR Access Date	2025-12-14 19:00:00
Issue	#10
File(s)	Simjacker_case_study.md, Screenshot-1.jpg
Recommendation	Unsuitable for MSCCS. Consider for CWE.

Review Summary

IMPORTANT: a complete review was not performed because the
vulnerability appears to be out of scope for MSCCS.

Writeup does not strictly follow case study structure, e.g. the use of
two hashes instead of three for section names. A syntax-checker report
could be made available.

The affected software is written in a proprietary language, which is
outside the scope of the MSCCS effort.

Vulnerability and Fix sections do not contain 'vulnerable file:' or
'fixed file:' labels respectively. Pseudocode is not suitable for this.

Recommendation: Not suitable for MSCCS. Consider for CWE as an
Observed Example or Demonstrative Example.

Case Study Structure

• writeup follows "Case Study Structure" recommendations without significant errors

Case Study Selection

• CVE
  • CVE ID clearly identified
  • CVE ID follows correct ID syntax
  • CVE is sufficiently recent
  • issue has been fixed
• Detailed reference(s)
  • vulnerable source code available
  • fixed source code available
  • code is properly licensed to be made public
  • (preferred) articles about exploitation

Case Study Contents

Title

• not too vague
• not too technical
• typically follows: <Weakness/Exploit Type> In <Software Name>
• generally between 4 and 6 words
• all caps

Introduction

• typically one paragraph
• issue and consequences in first sentence or two
• weakness type, possibly including position in Top 25
• sentence introducing the software application
• scope of the case study

Software

• has Name
  • include vendor name if applicable
  • avoid version numbers (in this field)
• has Language
• has URL (typically on GitHub if open source)

Weakness

• cites appropriate CWE ID and name
• one to two paragraphs long
• does not discuss the actual vulnerable code
• does not refer to the real software

Vulnerability

• CVE ID listed at the beginning
• discuss what the affected software is used for
• Code walk-through
  • calls out specific lines with language like "On line 123 ..."
  • calls out specific variables/inputs
  • includes "vulnerable file:" label and filename
  • follows "fenced code block" formatting
  • only cites source code that is necessary to the weakness
  • uses "..." to skip multiple lines of irrelevant source code
  • avoids exploit details

Exploit

• explain how the vulnerability is/was exploited and the consequences
• lists relevant CAPEC ID (if available)
• typically one to three paragraphs in length; could be longer with complex exploits
• when available, shows how certain inputs drive the exploit and how it works through the code

Fix

• describes how the weakness was fixed
• calls out specific lines with language like "On line 123 ..."
• focuses only on the changes related to the weakness
• code follows "fenced code block" formatting
• includes "fixed file:" label and filename
• uses ```diff construct to highlight the diff
• uses "..." to skip multiple lines of irrelevant source code

Prevention

• provides enough detail for the reader to implement the suggestions
• includes relevant secure coding practices
• includes mechanisms of identification e.g. tools
• typically a few paragraphs long

Conclusion

• brief summary of the case study (1 to 2 paragraphs long)
• avoids any new information

References

• name/URL of software page
• name/URL of the CVE
• name/URL of the CWE(s)
• name/URL of the CAPEC(s)
• name/URL of vendor's vuln report
• (if possible) name/URL of the specific code commit with the fix
• name/URL of any article that helped inform the case study
• no unusual/unexpected claims, or backed up by references
• (if available) name/URL for any foundational tutorial or best practice guide
• avoids listing all possible references

Contributors

• credits significant contributors
• includes original creator and reviewer(s)

Images/Diagrams (Optional)

• helps the reader understand a complex topic
• typically 0 to 2 images; no fixed rule