Make slack webhook detector regex more specific (#1168)

* Make slack webhook detector regex more specific

* fixup - add better body contains check

pkg/detectors/slackwebhook/slackwebhook.go

@@ -21,7 +21,7 @@ var (
 	client = common.SaneHttpClient()
 
 	// Make sure that your group is surrounded in boundary characters such as below to reduce false positives.
-	keyPat = regexp.MustCompile(`(https://hooks\.slack\.com/services/[A-Za-z0-9+/]{44,46})`)
+	keyPat = regexp.MustCompile(`(https://hooks\.slack\.com/services/T[A-Z0-9]+/B[A-Z0-9]+/[A-Za-z0-9]{23,25})`)
 )
 
 // Keywords are used for efficiently pre-filtering chunks.
@@ -62,7 +62,7 @@ func (s Scanner) FromData(ctx context.Context, verify bool, data []byte) (result
 					continue
 				}
 				body := string(bodyBytes)
-				if (res.StatusCode >= 200 && res.StatusCode < 300) || (res.StatusCode == 400 && strings.Contains(body, "text")) {
+				if (res.StatusCode >= 200 && res.StatusCode < 300) || (res.StatusCode == 400 && strings.Contains(body, "no_text")) {
 					s1.Verified = true
 				}
 			}