gas: A Go repository from NigelWan

GAS - Go AST Scanner

Inspects source code for security problems by scanning the Go AST.

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License here.

Project status

Gas is still in alpha and accepting feedback from early adopters. We do not consider it production ready at this time.

Install

$ go get github.com/GoASTScanner/gas/cmd/gas/...

Usage

Gas can be configured to only run a subset of rules, to exclude certain file paths, and produce reports in different formats. By default all rules will be run against the supplied input files. To recursively scan from the current directory you can supply './...' as the input argument.

Selecting rules

By default Gas will run all rules against the supplied file paths. It is however possible to select a subset of rules to run via the '-include=' flag, or to specify a set of rules to explicitly exclude using the '-exclude=' flag.

Available rules

G101: Look for hardcoded credentials
G102: Bind to all interfaces
G103: Audit the use of unsafe block
G104: Audit errors not checked
G105: Audit the use of math/big.Int.Exp
G106: Audit the use of ssh.InsecureIgnoreHostKey
G201: SQL query construction using format string
G202: SQL query construction using string concatenation
G203: Use of unescaped data in HTML templates
G204: Audit use of command execution
G301: Poor file permissions used when creating a directory
G302: Poor file permisions used with chmod
G303: Creating tempfile using a predictable path
G304: File path provided as taint input
G401: Detect the usage of DES, RC4, or MD5
G402: Look for bad TLS connection settings
G403: Ensure minimum RSA key length of 2048 bits
G404: Insecure random number source (rand)
G501: Import blacklist: crypto/md5
G502: Import blacklist: crypto/des
G503: Import blacklist: crypto/rc4
G504: Import blacklist: net/http/cgi

# Run a specific set of rules
$ gas -include=G101,G203,G401 ./...

# Run everything except for rule G303
$ gas -exclude=G303 ./...

Excluding files:

Gas will ignore dependencies in your vendor directory any files that are not considered build artifacts by the compiler (so test files).

Annotating code

As with all automated detection tools there will be cases of false positives. In cases where Gas reports a failure that has been manually verified as being safe it is possible to annotate the code with a '#nosec' comment.

The annotation causes Gas to stop processing any further nodes within the AST so can apply to a whole block or more granularly to a single expression.

import "md5" // #nosec


func main(){

    /* #nosec */
    if x > y {
        h := md5.New() // this will also be ignored
    }

}

In some cases you may also want to revisit places where #nosec annotations have been used. To run the scanner and ignore any #nosec annotations you can do the following:

$ gas -nosec=true ./...

Output formats

Gas currently supports text, json, yaml, csv and JUnit XML output formats. By default results will be reported to stdout, but can also be written to an output file. The output format is controlled by the '-fmt' flag, and the output file is controlled by the '-out' flag as follows:

# Write output in json format to results.json
$ gas -fmt=json -out=results.json *.go

Development

Prerequisites

Install dep according to the instructions here: https://github.com/golang/dep Install the latest version of golint: https://github.com/golang/lint

Build

make

Tests

make test

Release Build

Gas can be released as follows:

make release VERSION=2.0.0

The released version of the tool is available in the build folder. The build information should be displayed in the usage text.

./build/gas-2.0.0-linux-amd64 -h

GAS - Go AST Scanner

Gas analyzes Go source code to look for common programming mistakes that
can lead to security problems.

VERSION: 2.0.0
GIT TAG: 96489ff
BUILD DATE: 2018-02-21

Docker image

You can execute a release and build the docker image as follows:

make image VERSION=2.0.0

Now you can run the gas tool in a container against your local workspace:

docker run -it -v <YOUR LOCAL WORKSPACE>:/workspace gas /workspace

Generate TLS rule

The configuration of TLS rule can be generated from Mozilla's TLS ciphers recommendation.

First you need to install the generator tool:

go get github.com/GoASTScanner/gas/cmd/tlsconfig/...

You can invoke now the go generate in the root of the project:

go generate ./...

This will generate the rules/tls_config.go file with will contain the current ciphers recommendation from Mozilla.

NigelWan/gas