gosec/rules/hardcoded_credentials.go
2024-02-13 10:02:03 +01:00

394 lines
12 KiB
Go

// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
//
// 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 at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rules
import (
"fmt"
"go/ast"
"go/token"
"regexp"
"strconv"
zxcvbn "github.com/ccojocar/zxcvbn-go"
"github.com/securego/gosec/v2"
"github.com/securego/gosec/v2/issue"
)
type secretPattern struct {
name string
regexp *regexp.Regexp
}
var secretsPatterns = [...]secretPattern{
{
name: "RSA private key",
regexp: regexp.MustCompile(`-----BEGIN RSA PRIVATE KEY-----`),
},
{
name: "SSH (DSA) private key",
regexp: regexp.MustCompile(`-----BEGIN DSA PRIVATE KEY-----`),
},
{
name: "SSH (EC) private key",
regexp: regexp.MustCompile(`-----BEGIN EC PRIVATE KEY-----`),
},
{
name: "PGP private key block",
regexp: regexp.MustCompile(`-----BEGIN PGP PRIVATE KEY BLOCK-----`),
},
{
name: "Slack Token",
regexp: regexp.MustCompile(`xox[pborsa]-[0-9]{12}-[0-9]{12}-[0-9]{12}-[a-z0-9]{32}`),
},
{
name: "AWS API Key",
regexp: regexp.MustCompile(`AKIA[0-9A-Z]{16}`),
},
{
name: "Amazon MWS Auth Token",
regexp: regexp.MustCompile(`amzn\.mws\.[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`),
},
{
name: "AWS AppSync GraphQL Key",
regexp: regexp.MustCompile(`da2-[a-z0-9]{26}`),
},
{
name: "GitHub personal access token",
regexp: regexp.MustCompile(`ghp_[a-zA-Z0-9]{36}`),
},
{
name: "GitHub fine-grained access token",
regexp: regexp.MustCompile(`github_pat_[a-zA-Z0-9]{22}_[a-zA-Z0-9]{59}`),
},
{
name: "GitHub action temporary token",
regexp: regexp.MustCompile(`ghs_[a-zA-Z0-9]{36}`),
},
{
name: "Google API Key",
regexp: regexp.MustCompile(`AIza[0-9A-Za-z\-_]{35}`),
},
{
name: "Google Cloud Platform API Key",
regexp: regexp.MustCompile(`AIza[0-9A-Za-z\-_]{35}`),
},
{
name: "Google Cloud Platform OAuth",
regexp: regexp.MustCompile(`[0-9]+-[0-9A-Za-z_]{32}\.apps\.googleusercontent\.com`),
},
{
name: "Google Drive API Key",
regexp: regexp.MustCompile(`AIza[0-9A-Za-z\-_]{35}`),
},
{
name: "Google Drive OAuth",
regexp: regexp.MustCompile(`[0-9]+-[0-9A-Za-z_]{32}\.apps\.googleusercontent\.com`),
},
{
name: "Google (GCP) Service-account",
regexp: regexp.MustCompile(`"type": "service_account"`),
},
{
name: "Google Gmail API Key",
regexp: regexp.MustCompile(`AIza[0-9A-Za-z\-_]{35}`),
},
{
name: "Google Gmail OAuth",
regexp: regexp.MustCompile(`[0-9]+-[0-9A-Za-z_]{32}\.apps\.googleusercontent\.com`),
},
{
name: "Google OAuth Access Token",
regexp: regexp.MustCompile(`ya29\.[0-9A-Za-z\-_]+`),
},
{
name: "Google YouTube API Key",
regexp: regexp.MustCompile(`AIza[0-9A-Za-z\-_]{35}`),
},
{
name: "Google YouTube OAuth",
regexp: regexp.MustCompile(`[0-9]+-[0-9A-Za-z_]{32}\.apps\.googleusercontent\.com`),
},
{
name: "Generic API Key",
regexp: regexp.MustCompile(`[aA][pP][iI]_?[kK][eE][yY].*[''|"][0-9a-zA-Z]{32,45}[''|"]`),
},
{
name: "Generic Secret",
regexp: regexp.MustCompile(`[sS][eE][cC][rR][eE][tT].*[''|"][0-9a-zA-Z]{32,45}[''|"]`),
},
{
name: "Heroku API Key",
regexp: regexp.MustCompile(`[hH][eE][rR][oO][kK][uU].*[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}`),
},
{
name: "MailChimp API Key",
regexp: regexp.MustCompile(`[0-9a-f]{32}-us[0-9]{1,2}`),
},
{
name: "Mailgun API Key",
regexp: regexp.MustCompile(`key-[0-9a-zA-Z]{32}`),
},
{
name: "Password in URL",
regexp: regexp.MustCompile(`[a-zA-Z]{3,10}://[^/\\s:@]{3,20}:[^/\\s:@]{3,20}@.{1,100}["'\\s]`),
},
{
name: "Slack Webhook",
regexp: regexp.MustCompile(`https://hooks\.slack\.com/services/T[a-zA-Z0-9_]{8}/B[a-zA-Z0-9_]{8}/[a-zA-Z0-9_]{24}`),
},
{
name: "Stripe API Key",
regexp: regexp.MustCompile(`sk_live_[0-9a-zA-Z]{24}`),
},
{
name: "Stripe Restricted API Key",
regexp: regexp.MustCompile(`rk_live_[0-9a-zA-Z]{24}`),
},
{
name: "Square Access Token",
regexp: regexp.MustCompile(`sq0atp-[0-9A-Za-z\-_]{22}`),
},
{
name: "Square OAuth Secret",
regexp: regexp.MustCompile(`sq0csp-[0-9A-Za-z\-_]{43}`),
},
{
name: "Telegram Bot API Key",
regexp: regexp.MustCompile(`[0-9]+:AA[0-9A-Za-z\-_]{33}`),
},
{
name: "Twilio API Key",
regexp: regexp.MustCompile(`SK[0-9a-fA-F]{32}`),
},
{
name: "Twitter Access Token",
regexp: regexp.MustCompile(`[tT][wW][iI][tT][tT][eE][rR].*[1-9][0-9]+-[0-9a-zA-Z]{40}`),
},
{
name: "Twitter OAuth",
regexp: regexp.MustCompile(`[tT][wW][iI][tT][tT][eE][rR].*[''|"][0-9a-zA-Z]{35,44}[''|"]`),
},
}
type credentials struct {
issue.MetaData
pattern *regexp.Regexp
entropyThreshold float64
perCharThreshold float64
truncate int
ignoreEntropy bool
}
func (r *credentials) ID() string {
return r.MetaData.ID
}
func truncate(s string, n int) string {
if n > len(s) {
return s
}
return s[:n]
}
func (r *credentials) isHighEntropyString(str string) bool {
s := truncate(str, r.truncate)
info := zxcvbn.PasswordStrength(s, []string{})
entropyPerChar := info.Entropy / float64(len(s))
return (info.Entropy >= r.entropyThreshold ||
(info.Entropy >= (r.entropyThreshold/2) &&
entropyPerChar >= r.perCharThreshold))
}
func (r *credentials) isSecretPattern(str string) (bool, string) {
for _, pattern := range secretsPatterns {
if pattern.regexp.MatchString(str) {
return true, pattern.name
}
}
return false, ""
}
func (r *credentials) Match(n ast.Node, ctx *gosec.Context) (*issue.Issue, error) {
switch node := n.(type) {
case *ast.AssignStmt:
return r.matchAssign(node, ctx)
case *ast.ValueSpec:
return r.matchValueSpec(node, ctx)
case *ast.BinaryExpr:
return r.matchEqualityCheck(node, ctx)
}
return nil, nil
}
func (r *credentials) matchAssign(assign *ast.AssignStmt, ctx *gosec.Context) (*issue.Issue, error) {
for _, i := range assign.Lhs {
if ident, ok := i.(*ast.Ident); ok {
// First check LHS to find anything being assigned to variables whose name appears to be a cred
if r.pattern.MatchString(ident.Name) {
for _, e := range assign.Rhs {
if val, err := gosec.GetString(e); err == nil {
if r.ignoreEntropy || (!r.ignoreEntropy && r.isHighEntropyString(val)) {
return ctx.NewIssue(assign, r.ID(), r.What, r.Severity, r.Confidence), nil
}
}
}
}
// Now that no names were matched, match the RHS to see if the actual values being assigned are creds
for _, e := range assign.Rhs {
val, err := gosec.GetString(e)
if err != nil {
continue
}
if r.ignoreEntropy || r.isHighEntropyString(val) {
if ok, patternName := r.isSecretPattern(val); ok {
return ctx.NewIssue(assign, r.ID(), fmt.Sprintf("%s: %s", r.What, patternName), r.Severity, r.Confidence), nil
}
}
}
}
}
return nil, nil
}
func (r *credentials) matchValueSpec(valueSpec *ast.ValueSpec, ctx *gosec.Context) (*issue.Issue, error) {
// Running match against the variable name(s) first. Will catch any creds whose var name matches the pattern,
// then will go back over to check the values themselves.
for index, ident := range valueSpec.Names {
if r.pattern.MatchString(ident.Name) && valueSpec.Values != nil {
// const foo, bar = "same value"
if len(valueSpec.Values) <= index {
index = len(valueSpec.Values) - 1
}
if val, err := gosec.GetString(valueSpec.Values[index]); err == nil {
if r.ignoreEntropy || (!r.ignoreEntropy && r.isHighEntropyString(val)) {
return ctx.NewIssue(valueSpec, r.ID(), r.What, r.Severity, r.Confidence), nil
}
}
}
}
// Now that no variable names have been matched, match the actual values to find any creds
for _, ident := range valueSpec.Values {
if val, err := gosec.GetString(ident); err == nil {
if r.ignoreEntropy || r.isHighEntropyString(val) {
if ok, patternName := r.isSecretPattern(val); ok {
return ctx.NewIssue(valueSpec, r.ID(), fmt.Sprintf("%s: %s", r.What, patternName), r.Severity, r.Confidence), nil
}
}
}
}
return nil, nil
}
func (r *credentials) matchEqualityCheck(binaryExpr *ast.BinaryExpr, ctx *gosec.Context) (*issue.Issue, error) {
if binaryExpr.Op == token.EQL || binaryExpr.Op == token.NEQ {
ident, ok := binaryExpr.X.(*ast.Ident)
if !ok {
ident, _ = binaryExpr.Y.(*ast.Ident)
}
if ident != nil && r.pattern.MatchString(ident.Name) {
valueNode := binaryExpr.Y
if !ok {
valueNode = binaryExpr.X
}
if val, err := gosec.GetString(valueNode); err == nil {
if r.ignoreEntropy || (!r.ignoreEntropy && r.isHighEntropyString(val)) {
return ctx.NewIssue(binaryExpr, r.ID(), r.What, r.Severity, r.Confidence), nil
}
}
}
// Now that the variable names have been checked, and no matches were found, make sure that
// either the left or right operands is a string literal so we can match the value.
identStrConst, ok := binaryExpr.X.(*ast.BasicLit)
if !ok {
identStrConst, ok = binaryExpr.Y.(*ast.BasicLit)
}
if ok && identStrConst.Kind == token.STRING {
s, _ := gosec.GetString(identStrConst)
if r.ignoreEntropy || r.isHighEntropyString(s) {
if ok, patternName := r.isSecretPattern(s); ok {
return ctx.NewIssue(binaryExpr, r.ID(), fmt.Sprintf("%s: %s", r.What, patternName), r.Severity, r.Confidence), nil
}
}
}
}
return nil, nil
}
// NewHardcodedCredentials attempts to find high entropy string constants being
// assigned to variables that appear to be related to credentials.
func NewHardcodedCredentials(id string, conf gosec.Config) (gosec.Rule, []ast.Node) {
pattern := `(?i)passwd|pass|password|pwd|secret|token|pw|apiKey|bearer|cred`
entropyThreshold := 80.0
perCharThreshold := 3.0
ignoreEntropy := false
truncateString := 16
if val, ok := conf[id]; ok {
conf := val.(map[string]interface{})
if configPattern, ok := conf["pattern"]; ok {
if cfgPattern, ok := configPattern.(string); ok {
pattern = cfgPattern
}
}
if configIgnoreEntropy, ok := conf["ignore_entropy"]; ok {
if cfgIgnoreEntropy, ok := configIgnoreEntropy.(bool); ok {
ignoreEntropy = cfgIgnoreEntropy
}
}
if configEntropyThreshold, ok := conf["entropy_threshold"]; ok {
if cfgEntropyThreshold, ok := configEntropyThreshold.(string); ok {
if parsedNum, err := strconv.ParseFloat(cfgEntropyThreshold, 64); err == nil {
entropyThreshold = parsedNum
}
}
}
if configCharThreshold, ok := conf["per_char_threshold"]; ok {
if cfgCharThreshold, ok := configCharThreshold.(string); ok {
if parsedNum, err := strconv.ParseFloat(cfgCharThreshold, 64); err == nil {
perCharThreshold = parsedNum
}
}
}
if configTruncate, ok := conf["truncate"]; ok {
if cfgTruncate, ok := configTruncate.(string); ok {
if parsedInt, err := strconv.Atoi(cfgTruncate); err == nil {
truncateString = parsedInt
}
}
}
}
return &credentials{
pattern: regexp.MustCompile(pattern),
entropyThreshold: entropyThreshold,
perCharThreshold: perCharThreshold,
ignoreEntropy: ignoreEntropy,
truncate: truncateString,
MetaData: issue.MetaData{
ID: id,
What: "Potential hardcoded credentials",
Confidence: issue.Low,
Severity: issue.High,
},
}, []ast.Node{(*ast.AssignStmt)(nil), (*ast.ValueSpec)(nil), (*ast.BinaryExpr)(nil)}
}