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Caracal – Static Analyzer For Starknet Smart Contracts

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

NumDetectorWhat it DetectsImpactConfidenceCairo
1controlled-library-callLibrary calls with a user controlled class hashHighMedium1 & 2
2unchecked-l1-handler-fromDetect L1 handlers without from address checkHighMedium1 & 2
3felt252-overflowDetect user controlled operations with felt252 type, which is not overflow safeHighMedium1 & 2
4reentrancyDetect when a storage variable is read before an external call and written afterMediumMedium1 & 2
5read-only-reentrancyDetect when a view function read a storage variable written after an external callMediumMedium1 & 2
6unused-eventsEvents defined but not emittedMediumMedium1 & 2
7unused-returnUnused return valuesMediumMedium1 & 2
8unenforced-viewFunction has view decorator but modifies stateMediumMedium1
9unused-argumentsUnused argumentsLowMedium1 & 2
10reentrancy-benignDetect when a storage variable is written after an external call but not read beforeLowMedium1 & 2
11reentrancy-eventsDetect when an event is emitted after an external call leading to out-of-order eventsLowMedium1 & 2
12dead-codePrivate functions never usedLowMedium1 & 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.

Source : KitPloit – PenTest Tools!

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