Um usuário do Office 365 descobriu que cerca de 100 e-mails foram enviados aparentemente por ele; eles têm algum tipo de anexo PDF malicioso. Os cabeçalhos das mensagens mostram "Recebido: de XXX.XXX.PROD.OUTLOOK.COM" como origem inicial dos e-mails. Os emails enviados aparecem em um rastreamento de mensagens do Exchange Online para destinatários internos e externos. No entanto, eles não aparecem na pasta Itens Enviados do usuário.
Isso prova que alguém invadiu sua conta com sucesso (logado como ele) ou poderia haver outra explicação?
Preciso entender o que determina se um e-mail termina em Itens enviados e se um e-mail de saída pode estar no Rastreamento de mensagens sem que alguém efetue login como esse usuário.
Alteramos sua senha e verificamos se há malware em seu PC. Há mais alguma coisa que possa ser feita para evitar uma recorrência?
Atualização: Exemplo de cabeçalho de e-mail apenas ligeiramente redigido:
Received: from MM1P123MB1050.GBRP123.PROD.OUTLOOK.COM (10.166.235.24) by
MMXP123MB1376.GBRP123.PROD.OUTLOOK.COM with HTTPS via
MMXP123CA0017.GBRP123.PROD.OUTLOOK.COM; Fri, 16 Mar 2018 09:33:43 +0000
Authentication-Results: [somedomain].co.uk; dkim=none (message not signed)
header.d=none;[somedomain].co.uk; dmarc=none action=none
header.from=[somedomain].co.uk;
Received: from MM1P123MB1034.GBRP123.PROD.OUTLOOK.COM (10.166.217.148) by
MM1P123MB1050.GBRP123.PROD.OUTLOOK.COM (10.166.217.152) with Microsoft SMTP
Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id
15.20.588.14; Fri, 16 Mar 2018 09:33:40 +0000
Received: from MM1P123MB1034.GBRP123.PROD.OUTLOOK.COM
([fe80::bd23:2882:93cc:c179]) by MM1P123MB1034.GBRP123.PROD.OUTLOOK.COM
([fe80::bd23:2882:93cc:c179%14]) with mapi id 15.20.0588.016; Fri, 16 Mar
2018 09:33:39 +0000
Content-Type: application/ms-tnef; name="winmail.dat"
Content-Transfer-Encoding: binary
From: somename lastname <somename.lastname@[somedomain].co.uk>
Subject: Important New Document
Thread-Topic: Important New Document
Thread-Index: AQHTvQgYiGQw1JKKkUqd6+Gw0vjPcg==
Date: Fri, 16 Mar 2018 09:33:39 +0000
Message-ID: <MM1P123MB10344D41BCA2D78978E4E07AB2D70@MM1P123MB2034.GBRP123.PROD.OUTLOOK.COM>
Accept-Language: en-US
Content-Language: en-US
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MIME-Version: 1.0
X-MS-Exchange-Organization-MessageDirectionality: Originating
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To: Undisclosed recipients:;
Return-Path: somename.lastname@[somedomain].co.uk
X-MS-Office365-Filtering-Correlation-Id: c73bdaf1-0213-4e24-0323-08d58b210068
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Responder1
Eu diria que sim, parece que alguém tem suas credenciais do Outlook.com, pois o e-mail não foi falsificado, mas na verdade originado da Microsft.
Tivemos algo semelhante há 2 dias, onde um usuário recebeu um link falso em um e-mail falso para um documento que supostamente estava no OneDrive. Ao clicar no link, eles foram levados a um site falso solicitando suas credenciais. Depois de digitada, a conta do Outlook.com foi usada para enviar e-mails para qualquer endereço de e-mail que pudesse ser coletado - e assim o ciclo continua...
Em termos de ajudar a prevenir uma recorrência, 2FA e educação são suas opções :-)