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Um investigador de segurança desenvolveu uma nova técnica que pode ser explorada para quebrar facilmente as passwords WiFi da maioria dos routers, mesmo os mais modernos.

O investigador Jens “Atom” Steube, responsável pelo desenvolvimento da ferramenta Hashcat, criou uma nova técnica que pode ser usada para quebrar facilmente as passwords WiFi da maioria dos routers modernos.

A nova técnica de hacking permite crackar os protocolos de rede sem fio WPA / WPA2 com os recursos de roaming Pairwise Master Key Identifier (PMKID) ativos.

O especialista estava a analisar o recém-lançado padrão de segurança WPA3 quando acidentalmente “identificou e criou uma nova técnica”.

“This attack was discovered accidentally while looking for new ways to attack the new WPA3 security standard. WPA3 will be much harder to attack because of its modern key establishment protocol called “Simultaneous Authentication of Equals” (SAE).” Steube wrote in a post.

“The main difference from existing attacks is that in this attack, capture of a full EAPOL 4-way handshake is not required. The new attack is performed on the RSN IE (Robust Security Network Information Element) of a single EAPOL frame.”

 

Técnicas de ataque mais antigas exigiam a captura de um handshake completo de 4 vias do Protocolo de Autenticação Extensível via LAN (EAPOL), que é um protocolo de autenticação de porta de rede. A nova técnica de ataque, diferente das anteriores, tem como alvo o Elemento de Informação de Rede Robust Secure (RSN IE).

O protocolo RSN foi projetado para estabelecer comunicações seguras numa rede sem fios 802.11 e faz parte do padrão 802.11i (WPA). Toda vez que ele tenta estabelecer um canal de comunicação seguro, o RSN transmite uma mensagem do RSN IE dentro da rede.

wifi-hacking

O protocolo Robust Security Network possui o PMKID (Pairwise Master Key Identifier), que é a chave necessária para estabelecer uma conexão entre um cliente e um ponto de acesso.

Assim, um invasor pode obter a senha WPA PSK (Pre-Shared Key) do PMKID.

“Since the PMK is the same as in a regular EAPOL 4-way handshake this is an ideal attacking vector,” Steube added.

“We receive all the data we need in the first EAPOL frame from the AP.”

 

Abaixo da descrição da técnica, passo a passo:

Step 1 — An attacker can use a tool like hcxdumptool (v4.2.0 or higher) to request the PMKID from the targeted access point and dump the received frame to a file.

$ ./hcxdumptool -o test.pcapng -i wlp39s0f3u4u5 –enable_statusStep 2 — Run hcxpcaptool tool to convert the captured data from pcapng format to a hash format accepted by hashcat

$ ./hcxpcaptool -z test.16800 test.pcapng

Step 3 — Use Hashcat (v4.2.0 or higher) password cracking tool to obtain the WPA PSK (Pre-Shared Key) password that is the password of the target wireless network.

$ ./hashcat -m 16800 test.16800 -a 3 -w 3 ‘?l?l?l?l?l?lt!’The time to crack the password depends on its complexity.

“At this time, we do not know for which vendors or for how many routers this technique will work, but we think it will work against all 802.11i/p/q/r networks with roaming functions enabled (most modern routers).” Steube concluded.

“The main advantages of this attack are as follow:

  • No more regular users required – because the attacker directly communicates with the AP (aka “client-less” attack)
  • No more waiting for a complete 4-way handshake between the regular user and the AP
  • No more eventual retransmissions of EAPOL frames (which can lead to uncrackable results)
  • No more eventual invalid passwords sent by the regular user
  • No more lost EAPOL frames when the regular user or the AP is too far away from the attacker
  • No more fixing of nonce and replaycounter values required (resulting in slightly higher speeds)
  • No more special output format (pcaphccapx, etc.) – final data will appear as regular hex encoded string”

 

Se pretender seguir um tutorial passo a passo mais detalhado, esprite o post publicado pelo pentester Adam Toscher.

 

A nova técnica de ataque não funciona contra o recém-introduzido protocolo de segurança WPA3.

 

Pedro Tavares is a professional in the field of information security, working as an Ethical Hacker, Malware Analyst, Cybersecurity Analyst and also a Security Evangelist. He is also a founding member and Pentester at CSIRT.UBI and founder of the security computer blog seguranca-informatica.pt.

In recent years he has invested in the field of information security, exploring and analyzing a wide range of topics, such as pentesting (Kali Linux), malware, hacking, cybersecurity, IoT and security in computer networks.  He is also Freelance Writer.

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