Files
fscan/plugins/services/modbus.go
T

104 lines
2.4 KiB
Go

//go:build plugin_modbus || !plugin_selective
package services
import (
"context"
"encoding/binary"
"io"
"time"
"github.com/shadow1ng/fscan/common"
"github.com/shadow1ng/fscan/plugins"
)
type ModbusPlugin struct {
plugins.BasePlugin
}
func NewModbusPlugin() *ModbusPlugin {
return &ModbusPlugin{BasePlugin: plugins.NewBasePlugin("modbus")}
}
func (p *ModbusPlugin) Scan(ctx context.Context, info *common.HostInfo, session *common.ScanSession) *ScanResult {
timeout := session.Config.Timeout
if timeout <= 0 {
timeout = 3 * time.Second
}
addr := info.Target()
conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
if err != nil {
return &ScanResult{Success: false, Service: "modbus"}
}
defer conn.Close()
txID := randomUint16()
req := buildModbusDeviceIDRequest(txID)
_ = conn.SetDeadline(time.Now().Add(timeout))
if _, err := conn.Write(req); err != nil {
return &ScanResult{Success: false, Service: "modbus"}
}
header := make([]byte, 7)
if _, err := io.ReadFull(conn, header); err != nil {
return &ScanResult{Success: false, Service: "modbus"}
}
length := int(binary.BigEndian.Uint16(header[4:6]))
if length < 2 || length > 260 {
return &ScanResult{Success: false, Service: "modbus"}
}
body := make([]byte, length-1)
if _, err := io.ReadFull(conn, body); err != nil {
return &ScanResult{Success: false, Service: "modbus"}
}
banner, ok := parseModbusResponse(header, body, txID)
if !ok {
return &ScanResult{Success: false, Service: "modbus"}
}
return &ScanResult{
Success: true,
Type: plugins.ResultTypeService,
Service: "modbus",
Banner: banner,
}
}
func buildModbusDeviceIDRequest(txID uint16) []byte {
req := make([]byte, 11)
binary.BigEndian.PutUint16(req[0:2], txID)
binary.BigEndian.PutUint16(req[2:4], 0)
binary.BigEndian.PutUint16(req[4:6], 5)
req[6] = 0xff
req[7] = 0x2b
req[8] = 0x0e
req[9] = 0x01
req[10] = 0x00
return req
}
func parseModbusResponse(header, body []byte, txID uint16) (string, bool) {
if len(header) < 7 || len(body) < 1 {
return "", false
}
if binary.BigEndian.Uint16(header[0:2]) != txID || binary.BigEndian.Uint16(header[2:4]) != 0 {
return "", false
}
switch body[0] {
case 0x2b:
return "Modbus TCP device identification response", true
case 0xab:
return "Modbus TCP exception response", true
default:
return "", false
}
}
func init() {
RegisterPluginWithPorts("modbus", func() Plugin {
return NewModbusPlugin()
}, []int{502})
}