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package tschexec
import (
"context"
"encoding/xml"
"errors"
"fmt"
"github.com/FalconOpsLLC/goexec/internal/util"
dce "github.com/FalconOpsLLC/goexec/pkg/client/dcerpc"
"github.com/FalconOpsLLC/goexec/pkg/exec"
"github.com/bryanmcnulty/adauth"
"github.com/oiweiwei/go-msrpc/dcerpc"
"github.com/oiweiwei/go-msrpc/msrpc/tsch/itaskschedulerservice/v1"
"github.com/rs/zerolog"
"regexp"
"time"
)
const (
TaskXMLDurationFormat = "2006-01-02T15:04:05.9999999Z"
TaskXMLHeader = `<?xml version="1.0" encoding="UTF-16"?>`
)
var (
TaskPathRegex = regexp.MustCompile(`^\\[^ :/\\][^:/]*$`) // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-tsch/fa8809c8-4f0f-4c6d-994a-6c10308757c1
TaskNameRegex = regexp.MustCompile(`^[^ :/\\][^:/\\]*$`)
)
// *very* simple implementation of xs:duration - only accepts +seconds
func xmlDuration(dur time.Duration) string {
if s := int(dur.Seconds()); s >= 0 {
return fmt.Sprintf(`PT%dS`, s)
}
return `PT0S`
}
// Connect to the target & initialize DCE & TSCH clients
func (mod *Module) Connect(ctx context.Context, creds *adauth.Credential, target *adauth.Target) (err error) {
if mod.dce == nil {
mod.dce = dce.NewDCEClient(ctx, false, &dce.SmbConfig{})
if err = mod.dce.Connect(ctx, creds, target); err != nil {
return fmt.Errorf("DCE connect: %w", err)
} else if mod.tsch, err = itaskschedulerservice.NewTaskSchedulerServiceClient(ctx, mod.dce.DCE(), dcerpc.WithSecurityLevel(dcerpc.AuthLevelPktPrivacy)); err != nil {
return fmt.Errorf("init MS-TSCH client: %w", err)
}
mod.log.Info().Msg("DCE connection successful")
}
return
}
func (mod *Module) Cleanup(ctx context.Context, creds *adauth.Credential, target *adauth.Target, ccfg *exec.CleanupConfig) (err error) {
mod.log = zerolog.Ctx(ctx).With().
Str("module", "tsch").
Str("method", ccfg.CleanupMethod).Logger()
mod.creds = creds
mod.target = target
if ccfg.CleanupMethod == MethodDelete {
if cfg, ok := ccfg.CleanupMethodConfig.(MethodDeleteConfig); !ok {
return errors.New("invalid configuration")
} else {
if err = mod.Connect(ctx, creds, target); err != nil {
return fmt.Errorf("connect: %w", err)
} else if _, err = mod.tsch.Delete(ctx, &itaskschedulerservice.DeleteRequest{
Path: cfg.TaskPath,
Flags: 0,
}); err != nil {
mod.log.Error().Err(err).Str("task", cfg.TaskPath).Msg("Failed to delete task")
return fmt.Errorf("delete task: %w", err)
} else {
mod.log.Info().Str("task", cfg.TaskPath).Msg("Task deleted successfully")
}
}
} else {
return fmt.Errorf("method not implemented: %s", ccfg.CleanupMethod)
}
return
}
func (mod *Module) Exec(ctx context.Context, creds *adauth.Credential, target *adauth.Target, ecfg *exec.ExecutionConfig) (err error) {
mod.log = zerolog.Ctx(ctx).With().
Str("module", "tsch").
Str("method", ecfg.ExecutionMethod).Logger()
mod.creds = creds
mod.target = target
if ecfg.ExecutionMethod == MethodRegister {
if cfg, ok := ecfg.ExecutionMethodConfig.(MethodRegisterConfig); !ok {
return errors.New("invalid configuration")
} else {
startTime := time.Now().UTC().Add(cfg.StartDelay)
task := &task{
TaskVersion: "1.2", // static
TaskNamespace: "http://schemas.microsoft.com/windows/2004/02/mit/task", // static
TimeTriggers: []taskTimeTrigger{
{
StartBoundary: startTime.Format(TaskXMLDurationFormat),
Enabled: true,
},
},
Principals: defaultPrincipals,
Settings: defaultSettings,
Actions: actions{Context: defaultPrincipals.Principals[0].ID, Exec: []actionExec{{Command: ecfg.ExecutableName, Arguments: ecfg.ExecutableArgs}}},
}
if !cfg.NoDelete && !cfg.CallDelete {
if cfg.StopDelay == 0 {
// EndBoundary cannot be >= StartBoundary
cfg.StopDelay = 1 * time.Second
}
stopTime := startTime.Add(cfg.StopDelay)
mod.log.Info().Time("when", stopTime).Msg("Task is scheduled to delete")
task.Settings.DeleteExpiredTaskAfter = xmlDuration(cfg.DeleteDelay)
task.TimeTriggers[0].EndBoundary = stopTime.Format(TaskXMLDurationFormat)
}
if doc, err := xml.Marshal(task); err != nil {
return fmt.Errorf("marshal task XML: %w", err)
} else {
mod.log.Debug().Str("task", string(doc)).Msg("Task XML generated")
docStr := TaskXMLHeader + string(doc)
taskPath := cfg.TaskPath
taskName := cfg.TaskName
if taskName == "" {
taskName = util.RandomString()
}
if taskPath == "" {
taskPath = `\` + taskName
}
if err = mod.Connect(ctx, creds, target); err != nil {
return fmt.Errorf("connect: %w", err)
}
defer func() {
if err = mod.dce.Close(ctx); err != nil {
mod.log.Warn().Err(err).Msg("Failed to dispose dce client")
} else {
mod.log.Debug().Msg("Disposed DCE client")
}
}()
var response *itaskschedulerservice.RegisterTaskResponse
if response, err = mod.tsch.RegisterTask(ctx, &itaskschedulerservice.RegisterTaskRequest{
Path: taskPath,
XML: docStr,
Flags: 0, // TODO
LogonType: 0, // TASK_LOGON_NONE
CredsCount: 0,
Creds: nil,
}); err != nil {
return err
} else {
mod.log.Info().Str("path", response.ActualPath).Msg("Task registered successfully")
if !cfg.NoDelete && cfg.CallDelete {
defer func() {
if err = mod.Cleanup(ctx, creds, target, &exec.CleanupConfig{
CleanupMethod: MethodDelete,
CleanupMethodConfig: MethodDeleteConfig{TaskPath: taskPath},
}); err != nil {
mod.log.Error().Err(err).Msg("Failed to delete task")
}
}()
mod.log.Info().Dur("ms", cfg.StartDelay).Msg("Waiting for task to run")
select {
case <-ctx.Done():
mod.log.Warn().Msg("Cancelling execution")
return err
case <-time.After(cfg.StartDelay + (time.Second * 2)): // + two seconds
// TODO: check if task is running yet; delete if the wait period is over
break
}
return err
}
}
}
}
} else if ecfg.ExecutionMethod == MethodDemand {
if cfg, ok := ecfg.ExecutionMethodConfig.(MethodDemandConfig); !ok {
return errors.New("invalid configuration")
} else {
taskPath := cfg.TaskPath
taskName := cfg.TaskName
if taskName == "" {
mod.log.Debug().Msg("Task name not defined. Using random string")
taskName = util.RandomString()
}
if taskPath == "" {
taskPath = `\` + taskName
}
if !TaskNameRegex.MatchString(taskName) {
return fmt.Errorf("invalid task name: %s", taskName)
}
if !TaskPathRegex.MatchString(taskPath) {
return fmt.Errorf("invalid task path: %s", taskPath)
}
mod.log.Debug().Msg("Using demand method")
settings := defaultSettings
settings.AllowStartOnDemand = true
task := &task{
TaskVersion: "1.2", // static
TaskNamespace: "http://schemas.microsoft.com/windows/2004/02/mit/task", // static
Principals: defaultPrincipals,
Settings: defaultSettings,
Actions: actions{
Context: defaultPrincipals.Principals[0].ID,
Exec: []actionExec{
{
Command: ecfg.ExecutableName,
Arguments: ecfg.ExecutableArgs,
},
},
},
}
if doc, err := xml.Marshal(task); err != nil {
return fmt.Errorf("marshal task: %w", err)
} else {
docStr := TaskXMLHeader + string(doc)
if err = mod.Connect(ctx, creds, target); err != nil {
return fmt.Errorf("connect: %w", err)
}
defer func() {
if err = mod.dce.Close(ctx); err != nil {
mod.log.Warn().Err(err).Msg("Failed to dispose dce client")
} else {
mod.log.Debug().Msg("Disposed DCE client")
}
}()
var response *itaskschedulerservice.RegisterTaskResponse
if response, err = mod.tsch.RegisterTask(ctx, &itaskschedulerservice.RegisterTaskRequest{
Path: taskPath,
XML: docStr,
Flags: 0, // TODO
LogonType: 0, // TASK_LOGON_NONE
CredsCount: 0,
Creds: nil,
}); err != nil {
return fmt.Errorf("register task: %w", err)
} else {
mod.log.Info().Str("task", response.ActualPath).Msg("Task registered successfully")
if !cfg.NoDelete {
defer func() {
if err = mod.Cleanup(ctx, creds, target, &exec.CleanupConfig{
CleanupMethod: MethodDelete,
CleanupMethodConfig: MethodDeleteConfig{TaskPath: taskPath},
}); err != nil {
mod.log.Error().Err(err).Msg("Failed to delete task")
}
}()
}
if _, err = mod.tsch.Run(ctx, &itaskschedulerservice.RunRequest{
Path: response.ActualPath,
Flags: 0, // Maybe we want to use these?
}); err != nil {
return err
} else {
mod.log.Info().Str("task", response.ActualPath).Msg("Started task")
}
}
}
}
} else {
return fmt.Errorf("method not implemented: %s", ecfg.ExecutionMethod)
}
return nil
}
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