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cosmincojocar and gcmurphy Add an option for Go build tags (#201)
* Add an option for Go build tags

* Update README with a section for Go build tags
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.gitignore Use glide to manage vendored dependencies May 10, 2017
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README.md Add an option for Go build tags (#201) Apr 19, 2018
analyzer.go Add an option for Go build tags (#201) Apr 19, 2018
analyzer_test.go Add an option for Go build tags (#201) Apr 19, 2018
call_list.go Use explicit packages in call lists Jan 5, 2018
call_list_test.go Use explicit packages in call lists Jan 5, 2018
config.go address review comments Dec 14, 2017
config_test.go Major rework of codebase Jul 19, 2017
docker-entrypoint.sh Build improvments (#179) Mar 12, 2018
gas_suite_test.go Major rework of codebase Jul 19, 2017
helpers.go Major rework of codebase Jul 19, 2017
helpers_test.go actually skip tests until implementation exists Dec 13, 2017
import_tracker.go fix hound-ci errors Dec 13, 2017
issue.go Add the rule ID to issues (#188) Mar 12, 2018
issue_test.go Add the rule ID to issues (#188) Mar 12, 2018
resolve.go Major rework of codebase Jul 19, 2017
resolve_test.go Add test cases Sep 16, 2017
rule.go Add support for #excluding specific rules Mar 2, 2018
rule_test.go Add support for #excluding specific rules Mar 2, 2018


GAS - Go AST Scanner

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


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

Build Status GoDoc

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


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


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 ./...

Build tags

Gas is able to pass your Go build tags to the analyzer. They can be provided as a comma separated list as follows:

$ gas -tag debug,ignore ./...

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



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




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.