From c8126fc689d5965ca755e53c665aeabb3f043233 Mon Sep 17 00:00:00 2001 From: Joseph Goydish II Date: Fri, 19 Dec 2025 19:01:48 -0500 Subject: [PATCH] Add analysis-methods.md: describes all objective binary and trace analysis methods used in this investigation. --- docs/analysis-methods.md | 48 ++++++++++++++++------------------------ 1 file changed, 19 insertions(+), 29 deletions(-) diff --git a/docs/analysis-methods.md b/docs/analysis-methods.md index d376525..73143b5 100644 --- a/docs/analysis-methods.md +++ b/docs/analysis-methods.md @@ -1,35 +1,25 @@ # Analysis Methods -This document details only the objective methods and data sources used in the analysis of CS35L27 firmware. All narrative, interpretative, or speculative commentary has been excluded. +This document describes only the data sources and factual binary/trace analysis techniques used in this forensic investigation. -## Primary Data Sources -- Official CS35L27 firmware binary images. -- Publicly available datasheets and documentation from Cirrus Logic. -- Vendor-provided utilities for extracting firmware contents, where publicly redistributable. -- Open-source reverse engineering tools (e.g., Ghidra, Binwalk). +## Data Sources +- CS35L27 8051 firmware binary (Region 32, 4096 bytes) extracted from hardware. +- `codecctl.txt`: Registry and configuration dump obtained via device utilities; used for register offset and initialization value analysis. +- TraceV3 files: + - logdata_LiveData.tracev3 (3.3 MB) + - 00000000000076e4.tracev3 (7.6 MB) + - 000000000000442d.tracev3 (870 KB) + - 00000000000012fa.tracev3 (643 KB) + - 0000000000000005.timesync (46 KB) -## Objective Methods -### 1. Firmware Extraction -- Direct extraction of binary images from hardware or distribution files. -- Verification of image integrity through checksums or hashes. +## Objective Analysis Techniques -### 2. Binary Analysis -- Use of Ghidra and Binwalk for static analysis of binary structure. -- Identification and separation of code, data, and metadata sections. +- Static code analysis of 8051 binaries using Ghidra and Binwalk. +- String and pattern search via `strings`, regex, and custom scripts. +- Use of `codecctl.txt` for mapping register use and initialization state. +- Function boundary, call/return and jump/dispatch analysis via 8051 disassembly. +- Entropy mapping of binary regions for obfuscation/encryption checks. +- Systematic cross-check of firmware code/constant addresses with observed runtime behaviors in TraceV3 (hex and ASCII context). +- Counting and cataloging of event types including extended I2C commands, GPIO toggling, and I2S register values. -### 3. Strings and Pattern Search -- Systematic use of `strings` and regular expressions to locate text and code patterns in binaries. - -### 4. Function Identification -- Automated function boundary detection via Ghidra. -- Cross-referencing documented routines with observed binary segments. - -### 5. Data Extraction -- Extraction of configuration tables and constant data from designated binary offsets using custom scripts. - -### 6. Comparative Analysis -- Byte-wise and structural comparisons between multiple firmware images using `cmp`, `diff`, and custom tooling. - ---- - -All steps above use only publicly available tools and verifiable methods. No conclusions, narrative interpretations, or speculative extrapolations are included in this document. \ No newline at end of file +No non-public sources, inference, or speculation beyond direct result of binary/runtime/config file examination are recorded here.