Auto escape chars special to PowerShell in user supplied data

provisioner/powershell/provisioner.go

@@ -24,6 +24,13 @@ import (
 
 var retryableSleep = 2 * time.Second
 
+var psEscape = strings.NewReplacer(
+	"$", "`$",
+	"\"", "`\"",
+	"`", "``",
+	"'", "`'",
+)
+
 type Config struct {
 	common.PackerConfig `mapstructure:",squash"`
 
@@ -359,7 +366,13 @@ func (p *Provisioner) createFlattenedEnvVars(elevated bool) (flattened string) {
 	// Split vars into key/value components
 	for _, envVar := range p.config.Vars {
 		keyValue := strings.SplitN(envVar, "=", 2)
-		envVars[keyValue[0]] = keyValue[1]
+		// Escape chars special to PS in each env var value
+		escapedEnvVarValue := psEscape.Replace(keyValue[1])
+		if escapedEnvVarValue != keyValue[1] {
+			log.Printf("Env var %s converted to %s after escaping chars special to PS", keyValue[1],
+				escapedEnvVarValue)
+		}
+		envVars[keyValue[0]] = escapedEnvVarValue
 	}
 
 	// Create a list of env var keys in sorted order
@@ -480,13 +493,26 @@ func (p *Provisioner) generateElevatedRunner(command string) (uploadedPath strin
 	}
 	escapedCommand := buffer.String()
 	log.Printf("Command [%s] converted to [%s] for use in XML string", command, escapedCommand)
-
 	buffer.Reset()
 
+	// Escape chars special to PowerShell in the ElevatedUser string
+	escapedElevatedUser := psEscape.Replace(p.config.ElevatedUser)
+	if escapedElevatedUser != p.config.ElevatedUser {
+		log.Printf("Elevated user %s converted to %s after escaping chars special to PowerShell",
+			p.config.ElevatedUser, escapedElevatedUser)
+	}
+
+	// Escape chars special to PowerShell in the ElevatedPassword string
+	escapedElevatedPassword := psEscape.Replace(p.config.ElevatedPassword)
+	if escapedElevatedPassword != p.config.ElevatedPassword {
+		log.Printf("Elevated password %s converted to %s after escaping chars special to PowerShell",
+			p.config.ElevatedPassword, escapedElevatedPassword)
+	}
+
 	// Generate command
 	err = elevatedTemplate.Execute(&buffer, elevatedOptions{
-		User:              p.config.ElevatedUser,
+		User:              escapedElevatedUser,
-		Password:          p.config.ElevatedPassword,
+		Password:          escapedElevatedPassword,
 		TaskName:          taskName,
 		TaskDescription:   "Packer elevated task",
 		LogFile:           logFile,