Implement --env and --env-inheritance for 'execute' to allow greater control over subprocess env

client/command/exec/commands.go

@@ -25,12 +25,14 @@ func Commands(con *console.SliverClient) []*cobra.Command {
 	}
 	flags.Bind("", false, executeCmd, func(f *pflag.FlagSet) {
 		f.BoolP("token", "T", false, "execute command with current token (Windows only)")
-		f.BoolP("output", "o", false, "capture command output")
+		f.BoolP("output", "o", true, "capture command output")
 		f.BoolP("save", "s", false, "save output to a file")
 		f.BoolP("loot", "X", false, "save output as loot")
 		f.BoolP("ignore-stderr", "S", false, "don't print STDERR output")
 		f.StringP("stdout", "O", "", "remote path to redirect STDOUT to")
 		f.StringP("stderr", "E", "", "remote path to redirect STDERR to")
+		f.Bool("env-inheritance", true, "inherit environment variables from the current process")
+		f.StringArray("env", nil, "set an environment variable for the child process (key=value)")
 		f.StringP("name", "n", "", "name to assign loot (optional)")
 		f.Uint32P("ppid", "P", 0, "parent process id (optional, Windows only)")
 		f.BoolP("hidden", "H", false, "hide the window of the spawned process (Windows only)")

client/command/exec/execute.go

@@ -49,6 +49,13 @@ func ExecuteCmd(cmd *cobra.Command, con *console.SliverClient, args []string) {
 	saveLoot, _ := cmd.Flags().GetBool("loot")
 	saveOutput, _ := cmd.Flags().GetBool("save")
 	ppid, _ := cmd.Flags().GetUint32("ppid")
+	envInheritance, _ := cmd.Flags().GetBool("env-inheritance")
+	envPairs, _ := cmd.Flags().GetStringArray("env")
+	envVars, err := parseEnvPairs(envPairs)
+	if err != nil {
+		con.PrintErrorf("%s\n", err)
+		return
+	}
 	hostName := getHostname(session, beacon)
 
 	// If the user wants to loot or save the output, we have to capture it regardless of if they specified -o
@@ -59,15 +66,19 @@ func ExecuteCmd(cmd *cobra.Command, con *console.SliverClient, args []string) {
 	}
 
 	var exec *sliverpb.Execute
-	var err error
 
 	ctrl := make(chan bool)
+	con.PrintInfof("Execute: %s [%s]\n", cmdPath, strings.Join(args, " "))
 	con.SpinUntil(fmt.Sprintf("Executing %s %s ...", cmdPath, strings.Join(args, " ")), ctrl)
 	if token || hidden || ppid != 0 {
 		if (session != nil && session.OS != "windows") || (beacon != nil && beacon.OS != "windows") {
 			con.PrintErrorf("The token, hide window, and ppid options are not valid on %s\n", session.OS)
 			return
 		}
+		if envInheritance || len(envVars) > 0 {
+			con.PrintErrorf("The env and env-inheritance options are not supported with token, hidden, or ppid\n")
+			return
+		}
 		exec, err = con.Rpc.ExecuteWindows(context.Background(), &sliverpb.ExecuteWindowsReq{
 			Request:    con.ActiveTarget.Request(cmd),
 			Path:       cmdPath,
@@ -81,12 +92,14 @@ func ExecuteCmd(cmd *cobra.Command, con *console.SliverClient, args []string) {
 		})
 	} else {
 		exec, err = con.Rpc.Execute(context.Background(), &sliverpb.ExecuteReq{
-			Request: con.ActiveTarget.Request(cmd),
-			Path:    cmdPath,
-			Args:    args,
-			Output:  captureOutput,
-			Stderr:  stderr,
-			Stdout:  stdout,
+			Request:        con.ActiveTarget.Request(cmd),
+			Path:           cmdPath,
+			Args:           args,
+			Output:         captureOutput,
+			Stderr:         stderr,
+			Stdout:         stdout,
+			EnvInheritance: envInheritance,
+			Env:            envVars,
 		})
 	}
 	ctrl <- true
@@ -179,6 +192,21 @@ func getHostname(session *clientpb.Session, beacon *clientpb.Beacon) string {
 	return ""
 }
 
+func parseEnvPairs(envPairs []string) (map[string]string, error) {
+	if len(envPairs) == 0 {
+		return nil, nil
+	}
+	envVars := make(map[string]string, len(envPairs))
+	for _, pair := range envPairs {
+		parts := strings.SplitN(pair, "=", 2)
+		if len(parts) != 2 || parts[0] == "" {
+			return nil, fmt.Errorf("invalid --env value %q, expected key=value", pair)
+		}
+		envVars[parts[0]] = parts[1]
+	}
+	return envVars, nil
+}
+
 func determineCommandName(command string) string {
 	commandName := strings.ReplaceAll(command, "\\", "/")
 

client/command/help/long-help.go

@@ -68,6 +68,7 @@ var (
 		consts.RunAsStr:            runAsHelp,
 		consts.ImpersonateStr:      impersonateHelp,
 		consts.RevToSelfStr:        revToSelfHelp,
+		consts.ExecuteStr:          executeHelp,
 		consts.ExecuteAssemblyStr:  executeAssemblyHelp,
 		consts.ExecuteShellcodeStr: executeShellcodeHelp,
 		consts.MigrateStr:          migrateHelp,
@@ -124,6 +125,22 @@ var (
 		consts.C2ProfileStr + sep + consts.C2GenerateStr: c2GenerateHelp,
 	}
 
+	executeHelp = `[[.Bold]]Command:[[.Normal]] execute <path to executable> [options] -- [args...]
+
+[[.Bold]]About:[[.Normal]] Execute a program on the remote system with optional arguments, note the subprocess 
+arguments are be separated from the sliver 'execute' arguments with '--' 
+
+[[.Bold]]Example:[[.Normal]]
+execute /bin/bash --env FOO=1 -- -c env
+
+[*] Execute: /bin/bash [-c env]
+[*] Output:
+FOO=1
+PWD=/Users/moloch/git/sliver
+SHLVL=1
+_=/usr/bin/env
+`
+
 	jobsHelp = `[[.Bold]]Command:[[.Normal]] jobs <options>
 	[[.Bold]]About:[[.Normal]] Manage jobs/listeners.`
 

implant/sliver/handlers/handlers.go

@@ -27,10 +27,12 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"maps"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"regexp"
+	"sort"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -1146,6 +1148,29 @@ func executeHandler(data []byte, resp RPCResponse) {
 		return
 	}
 	cmd := exec.Command(exePath, execReq.Args...)
+	if execReq.EnvInheritance || len(execReq.Env) > 0 {
+		envVars := make(map[string]string)
+		if execReq.EnvInheritance {
+			for _, entry := range os.Environ() {
+				parts := strings.SplitN(entry, "=", 2)
+				if len(parts) == 2 {
+					envVars[parts[0]] = parts[1]
+				} else if len(parts) == 1 {
+					envVars[parts[0]] = ""
+				}
+			}
+		}
+		maps.Copy(envVars, execReq.Env)
+		keys := make([]string, 0, len(envVars))
+		for key := range envVars {
+			keys = append(keys, key)
+		}
+		sort.Strings(keys)
+		cmd.Env = make([]string, 0, len(envVars))
+		for _, key := range keys {
+			cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", key, envVars[key]))
+		}
+	}
 
 	if execReq.Output {
 		stdOutBuff := new(bytes.Buffer)

protobuf/sliverpb/sliver.proto

@@ -515,6 +515,9 @@ message ExecuteReq {
   bool Output = 3;
   string Stdout = 4;
   string Stderr = 5;
+  bool EnvInheritance = 6;
+  map<string, string> Env = 7;
+
   uint32 PPid = 10;
 
   commonpb.Request Request = 9;