CASR: Crash Analysis and Severity Report

CASR – collect crash (or UndefinedBehaviorSanitizer error) reports, triage, and estimate severity. It is based on ideas from exploitable and apport.

CASR is maintained by:

Overview

CASR is a set of tools that allows you to collect crash reports in different ways. Use casr-core binary to deal with coredumps. Use casr-san to analyze ASAN reports or casr-ubsan to analyze UBSAN reports. Try casr-gdb to get reports from gdb. Use casr-python to analyze python reports and get report from Atheris. Use casr-java to analyze java reports and get report from Jazzer. Use casr-js to analyze JavaScript reports and get report from Jazzer.js or jsfuzz. Use casr-csharp to analyze C# reports and get report from Sharpfuzz.

Crash report contains many useful information: severity (like exploitable) for x86, x86_64, arm32, aarch64, rv32g, rv64g architectures, OS and package versions, command line, stack trace, register values, disassembly, and even source code fragment where crash appeared. Reports are stored in JSON format. casr-cli is meant to provide TUI for viewing reports and converting them into SARIF report. Reports triage (deduplication, clustering) is done by casr-cluster. Triage is based on stack trace comparison from gdb-command. casr-afl is used to triage crashes found by AFL++ and AFL-based fuzzer Sharpfuzz. casr-libfuzzer can triage crashes found by libFuzzer based fuzzer (C/C++/go-fuzz/Atheris /Jazzer/Jazzer.js/ jsfuzz). casr-dojo allows to upload new and unique CASR reports to DefectDojo (available with dojo feature).

Explanation of severity classes could be found here. You could take a closer look at usage details here.

casr_report

casr_dojo_finding

LibCASR

LibCASR provides API for parsing stacktraces, collecting crash reports, triaging crashes (deduplication and clustering), and estimating severity of crashes.

It can analyze crashes from different sources:

AddressSanitizer
UndefinedBehaviorSanitizer
Gdb output

and program languages:

C/C++
Rust
Go
Python
Java
JavaScript
C#

It could be built with exploitable feature for severity estimation crashes collected from gdb. To save crash reports as json use serde feature.

Dependencies

Install runtime dependencies:

$ sudo apt install gdb lsb-release

Install build dependencies when building from source:

$ sudo apt install build-essential clang

Install Rust or update existing Rust installation:

$ rustup update

Install

Download latest Linux 64-bit release or build from source as explained below.

N.B. Current MacOS support is experimental. Some Linux-based code like exploitable and casr-gdb may not properly work. Further contributions are very much welcomed here.

Build from Git repository:

$ git clone https://github.com/ispras/casr
$ cargo update
$ cargo build --release

Or you may just install Casr from crates.io:

$ cargo install casr

Add dojo feature if you want to install casr-dojo (the same for cargo build):

$ cargo install -F dojo casr

Usage

Running in Docker: CASR disables address randomization for better deduplication and uses ptrace to run GDB. Thus, Docker should be started with --cap-add=SYS_PTRACE --security-opt seccomp=unconfined.

Create report from coredump:

$ casr-core -f casr/tests/casr_tests/bin/core.test_destAv -e casr/tests/casr_tests/bin/test_destAv -o destAv.casrep

Create report from AddressSanitizer output:

$ clang++ -fsanitize=address -O0 -g casr/tests/casr_tests/test_asan_df.cpp -o test_asan_df
$ casr-san -o asan.casrep -- ./test_asan_df

Create report from UndefinedBehaviorSanitizer output:

$ clang++ -fsanitize=undefined -O0 -g casr/tests/casr_tests/ubsan/test_ubsan.cpp -o test_ubsan
$ casr-ubsan -i casr/tests/casr_tests/ubsan/input1 -o output -- ./test_ubsan @@
$ casr-cli output

Create report from gdb:

$ casr-gdb -o destAv.gdb.casrep -- casr/tests/casr_tests/bin/test_destAv $(printf 'A%.s' {1..200})

Create report from python:

$ casr-python -o python.casrep -- casr/tests/casr_tests/python/test_casr_python.py

Create report from java:

$ casr-java -o java.casrep -- java casr/tests/casr_tests/java/Test1.java

Create report from JavaScript:

$ casr-js -o js.casrep -- node casr/tests/casr_tests/js/test_casr_js.js

Create report from C#:

$ casr-csharp -o csharp.casrep -- dotnet run --project casr/tests/casr_tests/csharp/test_casr_csharp/test_casr_csharp.csproj

View report:

$ casr-cli casr/tests/casr_tests/casrep/test_clustering_san/load_fuzzer_crash-120697a7f5b87c03020f321c8526adf0f4bcc2dc.casrep

View joint statistics about crash clusters:

$ casr-cli casr_reports

Convert reports to SARIF report:

$ casr-cli --sarif out.sarif --tool libfuzzer --source-root /xlnt casr/tests/casr_tests/casrep/test_clustering_san

Create report for program that reads stdin:

$ casr-san --stdin seed -o san_bin.casrep -- ./san_bin

Deduplicate reports:

$ casr-cluster -d casr/tests/casr_tests/casrep/test_clustering_gdb out-dedup

Cluster reports:

$ casr-cluster -c out-dedup out-cluster

Triage crashes after AFL++ fuzzing with casr-afl:

$ cp casr/tests/casr_tests/bin/load_afl /tmp/load_afl
$ cp casr/tests/casr_tests/bin/load_sydr /tmp/load_sydr
$ casr-afl -i casr/tests/casr_tests/casrep/afl-out-xlnt -o casr/tests/tmp_tests_casr/casr_afl_out
$ # You may also additionally generate crash reports for uninstrumented binary with casr-gdb
$ casr-afl -i casr/tests/casr_tests/casrep/afl-out-xlnt -o casr/tests/tmp_tests_casr/casr_afl_out -- /tmp/load_sydr @@

Triage crashes after Sharpfuzz fuzzing with casr-afl:

$ cp -r casr/tests/casr_tests/csharp/test_casr_afl_csharp /tmp/test_casr_afl_csharp
$ cp -r casr/tests/casr_tests/csharp/test_casr_afl_csharp_module /tmp/test_casr_afl_csharp_module
$ dotnet publish /tmp/test_casr_afl_csharp/test_casr_afl_csharp.csproj -c Debug -o /tmp/test_casr_afl_csharp/bin
$ casr-afl -i casr/tests/casr_tests/casrep/afl-out-sharpfuzz -o casr/tests/tmp_tests_casr/casr_afl_csharp_out
$ # You may force your own run arguments using --ignore-cmdline
$ casr-afl --ignore-cmdline -i casr/tests/casr_tests/casrep/afl-out-sharpfuzz -o casr/tests/tmp_tests_casr/casr_afl_csharp_out -- dotnet run --no-build --project /tmp/test_casr_afl_csharp/test_casr_afl_csharp.csproj @@

Triage libFuzzer crashes with casr-libfuzzer:

$ casr-libfuzzer -t 30 -i casr/tests/casr_tests/casrep/libfuzzer_crashes_xlnt -o casr/tests/tmp_tests_casr/casr_libfuzzer_out -- casr/tests/casr_tests/bin/load_fuzzer

Triage Atheris crashes with casr-libfuzzer:

$ unzip casr/tests/casr_tests/python/ruamel.zip
$ casr-libfuzzer -i casr/tests/casr_tests/casrep/atheris_crashes_ruamel_yaml -o casr/tests/tmp_tests_casr/casr_libfuzzer_atheris_out -- casr/tests/casr_tests/python/yaml_fuzzer.py

Triage Jazzer.js crashes with casr-libfuzzer (Jazzer.js installation guide):

$ unzip casr/tests/casr_tests/js/xml2js.zip -d xml2js
$ mkdir -p casr/tests/tmp_tests_casr/xml2js_fuzzer_out
$ cp casr/tests/casr_tests/js/test_casr_libfuzzer_jazzer_js_xml2js.js casr/tests/tmp_tests_casr/xml2js_fuzzer_out/xml2js_fuzzer.js
$ sudo npm install xml2js
$ sudo npm install --save-dev @jazzer.js/core
$ casr-libfuzzer -i ./xml2js -o casr/tests/tmp_tests_casr/xml2js_fuzzer_out/out -- npx jazzer casr/tests/tmp_tests_casr/xml2js_fuzzer_out/xml2js_fuzzer.js

Upload new and unique CASR reports to DefectDojo:

$ echo '[product]' > dojo.toml
$ echo 'name = "xlnt"' >> dojo.toml
$ echo '[engagement]' >> dojo.toml
$ echo "name = \"load_fuzzer $(date -Isec)\"" >> dojo.toml
$ echo '[test]' >> dojo.toml
$ echo 'test_type = "CASR DAST Report"' >> dojo.toml
$ casr-dojo -i casr/tests/casr_tests/casrep/test_clustering_san -u http://localhost:8080 -t 382f5dfdf2a339f7c3bb35442f9deb9b788a98d5 dojo.toml

Fuzzing Crash Triage Pipeline

When you have crashes from fuzzing you may do the following steps:

Create reports for all crashes via casr-san, casr-gdb (if no sanitizers are present), casr-python, casr-java, casr-js, or casr-csharp.
Deduplicate collected crash reports via casr-cluster -d.
Cluster deduplicated crash reports via casr-cluster -c.
Create reports and deduplicate them for all UBSAN errors via casr-ubsan.
View reports from clusters using casr-cli or upload them to DefectDojo with casr-dojo.

If you use AFL++ or AFL-based fuzzer Sharpfuzz, the pipeline (without casr-ubsan and casr-dojo) could be done automatically by casr-afl.

If you use libFuzzer based fuzzer (C/C++/go-fuzz/Atheris /Jazzer/Jazzer.js/ jsfuzz), the pipeline (without casr-ubsan and casr-dojo) could be done automatically by casr-libfuzzer.

Contributing

Feel free to open issues or PRs (especially pay attention to help wanted issues)! We appreciate your support!

Please follow the next recommendations for your pull requests:

compile with stable rust
use cargo fmt
check the output of cargo clippy --all-features --all --tests
run tests cargo test
if you have updated usage of any casr tool, you could simply run update_usage.py to change the docs/usage.md file properly

Cite Us

Savidov G., Fedotov A. Casr-Cluster: Crash Clustering for Linux Applications. 2021 Ivannikov ISPRAS Open Conference (ISPRAS), IEEE, 2021, pp. 47-51. DOI: 10.1109/ISPRAS53967.2021.00012 [paper] [slides]

@inproceedings{savidov2021casr,
  title = {{{Casr-Cluster}}: Crash Clustering for Linux Applications},
  author = {Savidov, Georgy and Fedotov, Andrey},
  booktitle = {2021 Ivannikov ISPRAS Open Conference (ISPRAS)},
  pages = {47--51},
  year = {2021},
  organization = {IEEE},
  doi = {10.1109/ISPRAS53967.2021.00012},
}

Andrey Fedotov, Alexey Vishnyakov. CASR: Your Life Vest in a Sea of Crashes. OFFZONE 2023. [slides] [russian video]

Yegorov I., Savidov G. Crash Report Accumulation During Continuous Fuzzing with CASR. Ivannikov Memorial Workshop 2024, IEEE, 2024. [paper] [slides] [russian video]

@inproceedings{yegorov2024accum,
  title = {Crash Report Accumulation During Continuous Fuzzing},
  author = {Yegorov, Ilya and Savidov, Georgy},
  booktitle = {Ivannikov Memorial Workshop 2024},
  publisher = {IEEE},
  year = {2024},
  url = {https://arxiv.org/abs/2405.18174},
}

License

Licensed under Apache-2.0.

ispras / casr

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