[Feat] Detector implementation for Azure SAS Tokens (#3963)

* azure sas token detector implementation

* regex optimization and some refactoring of code.

* fixed breaking changes.

* change regex to support allowed Ip address

* remove stdout printing statements.
used background context for individual test.

* implemented CustomFalsePositiveChecker for Azure SAS detector.

* raise verification error on restricted ip address

* cache and skip invalid hosts

* some refactoring

* fix spelling mistake

* added more positive and negative test cases

* add test inputs directly in tests instead of declaring separately

Author: abmussani

pkg/detectors/azuresastoken/azuresastoken.go

@@ -0,0 +1,157 @@
+package azuresastoken
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	regexp "github.com/wasilibs/go-re2"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/cache/simple"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/common"
+	logContext "github.com/trufflesecurity/trufflehog/v3/pkg/context"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/detectors"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/pb/detectorspb"
+)
+
+type Scanner struct {
+	client *http.Client
+	detectors.DefaultMultiPartCredentialProvider
+}
+
+var _ detectors.Detector = (*Scanner)(nil)
+var _ detectors.CustomFalsePositiveChecker = (*Scanner)(nil)
+
+var (
+	defaultClient = common.SaneHttpClient()
+
+	// microsoft storage resource naming rules: https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/resource-name-rules#microsoftstorage:~:text=format%3A%0AVaultName_KeyName_KeyVersion.-,Microsoft.Storage,-Expand%20table
+	urlPat = regexp.MustCompile(`https://([a-zA-Z0-9][a-z0-9_-]{1,22}[a-zA-Z0-9])\.blob\.core\.windows\.net/[a-z0-9]([a-z0-9-]{1,61}[a-z0-9])?(?:/[a-zA-Z0-9._-]+)*`)
+
+	keyPat = regexp.MustCompile(
+		detectors.PrefixRegex([]string{"azure", "sas", "token", "blob", ".blob.core.windows.net"}) +
+			`(sp=[racwdli]+&st=\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z&se=\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z(?:&sip=\d{1,3}(?:\.\d{1,3}){3}(?:-\d{1,3}(?:\.\d{1,3}){3})?)?(&spr=https)?(?:,https)?&sv=\d{4}-\d{2}-\d{2}&sr=[bcfso]&sig=[a-zA-Z0-9%]{10,})`)
+
+	invalidStorageAccounts = simple.NewCache[struct{}]()
+
+	noSuchHostErr = errors.New("no such host")
+)
+
+func (s Scanner) Keywords() []string {
+	return []string{
+		"azure",
+		".blob.core.windows.net",
+	}
+}
+
+func (s Scanner) Type() detectorspb.DetectorType {
+	return detectorspb.DetectorType_AzureSasToken
+}
+
+func (s Scanner) Description() string {
+	return "An Azure Shared Access Signature (SAS) token is a time-limited, permission-based URL query string that grants secure, granular access to Azure Storage resources (e.g., blobs, containers, files) without exposing account keys."
+}
+
+func (s Scanner) FromData(ctx context.Context, verify bool, data []byte) (results []detectors.Result, err error) {
+	logger := logContext.AddLogger(ctx).Logger().WithName("azuresas")
+
+	dataStr := string(data)
+
+	// deduplicate urlMatches
+	urlMatchesUnique := make(map[string]string)
+	for _, urlMatch := range urlPat.FindAllStringSubmatch(dataStr, -1) {
+		urlMatchesUnique[urlMatch[0]] = urlMatch[1]
+	}
+
+	// deduplicate keyMatches
+	keyMatchesUnique := make(map[string]struct{})
+	for _, keyMatch := range keyPat.FindAllStringSubmatch(dataStr, -1) {
+		keyMatchesUnique[keyMatch[1]] = struct{}{}
+	}
+
+	// Check results.
+UrlLoop:
+	for url, storageAccount := range urlMatchesUnique {
+		for key := range keyMatchesUnique {
+			s1 := detectors.Result{
+				DetectorType: detectorspb.DetectorType_AzureSasToken,
+				Raw:          []byte(url),
+				RawV2:        []byte(url + key),
+			}
+
+			if verify {
+				if invalidStorageAccounts.Exists(storageAccount) {
+					logger.V(3).Info("Skipping invalid storage account", "storage account", storageAccount)
+					break
+				}
+
+				client := s.client
+				if client == nil {
+					client = defaultClient
+				}
+
+				isVerified, verificationErr := verifyMatch(ctx, client, url, key, true)
+				s1.Verified = isVerified
+
+				if verificationErr != nil {
+					if errors.Is(verificationErr, noSuchHostErr) {
+						invalidStorageAccounts.Set(storageAccount, struct{}{})
+						continue UrlLoop
+					}
+					s1.SetVerificationError(verificationErr, key)
+				}
+			}
+
+			results = append(results, s1)
+		}
+	}
+
+	return results, nil
+}
+
+func (s Scanner) IsFalsePositive(_ detectors.Result) (bool, string) {
+	return false, ""
+}
+
+func verifyMatch(ctx context.Context, client *http.Client, url, key string, retryOn403 bool) (bool, error) {
+	urlWithToken := url + "?" + key
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, urlWithToken, nil)
+	if err != nil {
+		return false, err
+	}
+
+	res, err := client.Do(req)
+	if err != nil {
+		if strings.Contains(err.Error(), "no such host") {
+			return false, noSuchHostErr
+		}
+		return false, err
+	}
+	defer res.Body.Close()
+
+	bodyBytes, err := io.ReadAll(res.Body)
+	if err != nil {
+		return false, err
+	}
+
+	switch res.StatusCode {
+	case http.StatusOK:
+		return true, nil
+	case http.StatusForbidden:
+		if retryOn403 && strings.Contains(string(bodyBytes), "Signature did not match") {
+			// need to add additional query parameters for container urls
+			// https://stackoverflow.com/questions/25038429/azure-shared-access-signature-signature-did-not-match
+			return verifyMatch(ctx, client, url, key+"&comp=list&restype=container", false)
+		}
+		if strings.Contains(string(bodyBytes), "AuthorizationFailure") && strings.Contains(key, "&sip=") {
+			return false, fmt.Errorf("SAS token is restricted to specific IP addresses")
+		}
+		return false, nil
+	default:
+		return false, fmt.Errorf("unexpected HTTP response status %d", res.StatusCode)
+	}
+}

pkg/detectors/azuresastoken/azuresastoken_integration_test.go

@@ -0,0 +1,129 @@
+//go:build detectors
+// +build detectors
+
+package azuresastoken
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/common"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/detectors"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/pb/detectorspb"
+)
+
+func TestAzureSasToken_FromChunk(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+	testSecrets, err := common.GetSecret(ctx, "trufflehog-testing", "detectors5")
+	if err != nil {
+		t.Fatalf("could not get test secrets from GCP: %s", err)
+	}
+	url := testSecrets.MustGetField("AZURESASTOKEN_URL")
+	secret := testSecrets.MustGetField("AZURESASTOKEN")
+	inactiveSecret := testSecrets.MustGetField("AZURESASTOKEN_INACTIVE")
+
+	type args struct {
+		ctx    context.Context
+		data   []byte
+		verify bool
+	}
+	tests := []struct {
+		name                string
+		s                   Scanner
+		args                args
+		want                []detectors.Result
+		wantErr             bool
+		wantVerificationErr bool
+	}{
+		{
+			name: "found, verified",
+			s:    Scanner{},
+			args: args{
+				ctx:    context.Background(),
+				data:   []byte(fmt.Sprintf("You can find a azure sas url %s and token %s within", url, secret)),
+				verify: true,
+			},
+			want: []detectors.Result{
+				{
+					DetectorType: detectorspb.DetectorType_AzureSasToken,
+					Verified:     true,
+				},
+			},
+			wantErr:             false,
+			wantVerificationErr: false,
+		},
+		{
+			name: "found, unverified",
+			s:    Scanner{},
+			args: args{
+				ctx:    context.Background(),
+				data:   []byte(fmt.Sprintf("You can find a azure sas url %s and token %s within but not valid", url, inactiveSecret)), // the secret would satisfy the regex but not pass validation
+				verify: true,
+			},
+			want: []detectors.Result{
+				{
+					DetectorType: detectorspb.DetectorType_AzureSasToken,
+					Verified:     false,
+				},
+			},
+			wantErr:             false,
+			wantVerificationErr: false,
+		},
+		{
+			name: "not found",
+			s:    Scanner{},
+			args: args{
+				ctx:    context.Background(),
+				data:   []byte("You cannot find the secret within"),
+				verify: true,
+			},
+			want:                nil,
+			wantErr:             false,
+			wantVerificationErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.s.FromData(tt.args.ctx, tt.args.verify, tt.args.data)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("AzureSasToken.FromData() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			for i := range got {
+				if len(got[i].Raw) == 0 {
+					t.Fatalf("no raw secret present: \n %+v", got[i])
+				}
+				if (got[i].VerificationError() != nil) != tt.wantVerificationErr {
+					t.Fatalf("wantVerificationError = %v, verification error = %v", tt.wantVerificationErr, got[i].VerificationError())
+				}
+			}
+			ignoreOpts := cmpopts.IgnoreFields(detectors.Result{}, "Raw", "RawV2", "Redacted", "verificationError")
+			if diff := cmp.Diff(got, tt.want, ignoreOpts); diff != "" {
+				t.Errorf("AzureSasToken.FromData() %s diff: (-got +want)\n%s", tt.name, diff)
+			}
+		})
+	}
+}
+
+func BenchmarkFromData(benchmark *testing.B) {
+	ctx := context.Background()
+	s := Scanner{}
+	for name, data := range detectors.MustGetBenchmarkData() {
+		benchmark.Run(name, func(b *testing.B) {
+			b.ResetTimer()
+			for n := 0; n < b.N; n++ {
+				_, err := s.FromData(ctx, false, data)
+				if err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}