CASR: Crash Analysis and Severity Report

CASR – collect crash reports, triage, and estimate severity. It is based on ideas from exploitable and apport.

CASR is maintained by:

• Andrey Fedotov \
• Alexey Vishnyakov \
• Georgy Savidov \
• Ilya Yegorov \

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. Try casr-gdb to get reports from gdb. Use casr-python to analyze python reports and get report from atheris.

Crash report contains many useful information: severity (like exploitable), 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. 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++.

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

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
• Gdb output

and program languages:

• C/C++
• Rust
• Go
• Python

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

Getting started

1. Install Rust. Instructions can be found here.
2. Clone CASR repository:

$ git clone https://github.com/ispras/casr 3. Build CASR:

$ cargo build --release 4. Install runtime dependencies:

$ sudo apt install gdb python3 python3-pip lsb-release $ sudo -H python3 -m pip install numpy scipy

Instead of steps 2-3 you may just install Casr from crates.io:

$ cargo install casr

Usage

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 sanitizers 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 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

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

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/bin/afl-out-xlnt -o casr/tests/tmp_tests_casr/casr_afl_out

Fuzzing Crash Triage Pipeline

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

1. Create reports for all crashes via casr-san or casr-gdb (if no sanitizers are present).
2. Deduplicate collected reports via casr-cluster -d.
3. Cluster deduplicated reports via casr-cluster -c.
4. View reports from clusters using casr-cli.

If you use AFL++ steps from 1 to 3 could be done automatically by casr-afl.

Contributing

Feel free to open issues or PRs! 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
• run tests cargo test

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]

bibtex @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}, }

License

Licensed under Apache-2.0.