Caracal - Static Analyzer For Starknet Smart Contracts

By: Zion3R — October 6^th 2023 at 11:30

Caracal is a static analyzer tool over the SIERRA representation for Starknet smart contracts.

Features

Detectors to detect vulnerable Cairo code
Printers to report information
Taint analysis
Data flow analysis framework
Easy to run in Scarb projects

Installation

Precompiled binaries

Precompiled binaries are available on our releases page. If you are using Cairo compiler 1.x.x uses the binary v0.1.x otherwise if you are using the Cairo compiler 2.x.x uses v0.2.x.

Building from source

You need the Rust compiler and Cargo. Building from git:

cargo install --git https://github.com/crytic/caracal --profile release --force

Building from a local copy:

git clone https://github.com/crytic/caracal
cd caracal
cargo install --path . --profile release --force

Usage

List detectors:

caracal detectors

List printers:

caracal printers

Standalone

To use with a standalone cairo file you need to pass the path to the corelib library either with the --corelib cli option or by setting the CORELIB_PATH environment variable. Run detectors:

caracal detect path/file/to/analyze --corelib path/to/corelib/src

Run printers:

caracal print path/file/to/analyze --printer printer_to_use --corelib path/to/corelib/src

Scarb

If you have a project that uses Scarb you need to add the following in Scarb.toml:

[[target.starknet-contract]]
sierra = true

[cairo]
sierra-replace-ids = true

Then pass the path to the directory where Scarb.toml resides. Run detectors:

caracal detect path/to/dir

Run printers:

caracal print path/to/dir --printer printer_to_use

Detectors

Num	Detector	What it Detects	Impact	Confidence	Cairo
1	`controlled-library-call`	Library calls with a user controlled class hash	High	Medium	1 & 2
2	`unchecked-l1-handler-from`	Detect L1 handlers without from address check	High	Medium	1 & 2
3	`felt252-overflow`	Detect user controlled operations with felt252 type, which is not overflow safe	High	Medium	1 & 2
4	`reentrancy`	Detect when a storage variable is read before an external call and written after	Medium	Medium	1 & 2
5	`read-only-reentrancy`	Detect when a view function read a storage variable written after an external call	Medium	Medium	1 & 2
6	`unused-events`	Events defined but not emitted	Medium	Medium	1 & 2
7	`unused-return`	Unused return values	Medium	Medium	1 & 2
8	`unenforced-view`	Function has view decorator but modifies state	Medium	Medium	1
9	`unused-arguments`	Unused arguments	Low	Medium	1 & 2
10	`reentrancy-benign`	Detect when a storage variable is written after an external call but not read before	Low	Medium	1 & 2
11	`reentrancy-events`	Detect when an event is emitted after an external call leading to out-of-order events	Low	Medium	1 & 2
12	`dead-code`	Private functions never used	Low	Medium	1 & 2

The Cairo column represent the compiler version(s) for which the detector is valid.

Printers

cfg: Export the CFG of each function to a .dot file
callgraph: Export function call graph to a .dot file

How to contribute

Check the wiki on the following topics:

Limitations

Inlined functions are not handled correctly.
Since it's working over the SIERRA representation it's not possible to report where an error is in the source code but we can only report SIERRA instructions/what's available in a SIERRA program.

Download Caracal

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