| # System Sanitizers | |
| We use `ptrace` to instrument system calls made by the target program to detect | |
| various vulnerabilities. | |
| ## Command injection | |
| This detector currently works by | |
| - Checking if `execve` is called with `/tmp/tripwire` (which comes from our dictionary). | |
| - Checking if `execve` is invoking a shell with invalid syntax. This is likely | |
| caused by our input. | |
| ## Arbitrary file open | |
| TODO: documentation. | |
| ## Proof of concept | |
| ### Cleanup | |
| Note this will delete /tmp/tripwire if it exists. | |
| ```shell | |
| make clean | |
| ``` | |
| ### Run test | |
| Note this will overwrite /tmp/tripwire if it exists. | |
| ```shell | |
| make test | |
| ``` | |
| Look for one of the following lines: | |
| > ===BUG DETECTED: Shell injection=== | |
| which indicates the detection of executing the planted `/tmp/tripwire`. | |
| > ===BUG DETECTED: Shell corruption=== | |
| which indicates the detection of executing a syntactic erroneous command. | |
| ### Command injection PoC in Python with `pytorch-lightning` | |
| With `SystemSan`, [`Artheris`](https://github.com/google/atheris) can detect a shell injection bug in [version v1.5.10 of `pytorch-lightning`](https://github.com/PyTorchLightning/pytorch-lightning/tree/1.5.0). | |
| ```shell | |
| make pytorch-lightning-1.5.10 | |
| ``` | |
| ### Command injection PoC in JavaScript with `shell-quote` | |
| With `SystemSan`, [`Jsfuzz`](https://gitlab.com/gitlab-org/security-products/analyzers/fuzzers/jsfuzz) can detect a shell corrpution bug in [the latest version (v1.7.3) of `shell-quote`](https://github.com/substack/node-shell-quote) without any seed. | |
| ```shell | |
| make node-shell-quote-v1.7.3 | |
| ``` | |
| This is based on [a shell injection exploit report](https://wh0.github.io/2021/10/28/shell-quote-rce-exploiting.html) of [version v1.7.2 of `shell-quote`](https://github.com/substack/node-shell-quote/tree/v1.7.2). | |
| `SystemSan` can also discover the same shell injection bug with a corpus file containing: | |
| ``` | |
| `:`/tmp/tripwire``:` | |
| ``` | |
| ## Trophies | |
| - <https://github.com/syoyo/tinygltf/issues/368> | |
| - <https://github.com/substack/node-shell-quote/issues/54> | |