Hide Artifacts: Правила для сокрытия писем
Other sub-techniques of Hide Artifacts (14)
Adversaries may use email rules to hide inbound emails in a compromised user's mailbox. Many email clients allow users to create inbox rules for various email functions, including moving emails to other folders, marking emails as read, or deleting emails. Rules may be created or modified within email clients or through external features such as the New-InboxRule or Set-InboxRule PowerShell cmdlets on Windows systems.(Citation: Microsoft Inbox Rules)(Citation: MacOS Email Rules)(Citation: Microsoft New-InboxRule)(Citation: Microsoft Set-InboxRule)
Adversaries may utilize email rules within a compromised user's mailbox to delete and/or move emails to less noticeable folders. Adversaries may do this to hide security alerts, C2 communication, or responses to Internal Spearphishing emails sent from the compromised account.
Any user or administrator within the organization (or adversary with valid credentials) may be able to create rules to automatically move or delete emails. These rules can be abused to impair/delay detection had the email content been immediately seen by a user or defender. Malicious rules commonly filter out emails based on key words (such as malware, suspicious, phish, and hack) found in message bodies and subject lines. (Citation: Microsoft Cloud App Security)
In some environments, administrators may be able to enable email rules that operate organization-wide rather than on individual inboxes. For example, Microsoft Exchange supports transport rules that evaluate all mail an organization receives against user-specified conditions, then performs a user-specified action on mail that adheres to those conditions.(Citation: Microsoft Mail Flow Rules 2023) Adversaries that abuse such features may be able to automatically modify or delete all emails related to specific topics (such as internal security incident notifications).
Примеры процедур |
|
| Название | Описание |
|---|---|
| Scattered Spider |
Scattered Spider creates inbound rules on the compromised email accounts of security personnel to automatically delete emails from vendor security products.(Citation: MSTIC Octo Tempest Operations October 2023) |
| FIN4 |
FIN4 has created rules in victims' Microsoft Outlook accounts to automatically delete emails containing words such as “hacked," "phish," and “malware" in a likely attempt to prevent organizations from communicating about their activities.(Citation: FireEye Hacking FIN4 Dec 2014) |
Контрмеры |
|
| Контрмера | Описание |
|---|---|
| Audit |
Auditing is the process of recording activity and systematically reviewing and analyzing the activity and system configurations. The primary purpose of auditing is to detect anomalies and identify potential threats or weaknesses in the environment. Proper auditing configurations can also help to meet compliance requirements. The process of auditing encompasses regular analysis of user behaviors and system logs in support of proactive security measures. Auditing is applicable to all systems used within an organization, from the front door of a building to accessing a file on a fileserver. It is considered more critical for regulated industries such as, healthcare, finance and government where compliance requirements demand stringent tracking of user and system activates.This mitigation can be implemented through the following measures: System Audit: - Use Case: Regularly assess system configurations to ensure compliance with organizational security policies. - Implementation: Use tools to scan for deviations from established benchmarks. Permission Audits: - Use Case: Review file and folder permissions to minimize the risk of unauthorized access or privilege escalation. - Implementation: Run access reviews to identify users or groups with excessive permissions. Software Audits: - Use Case: Identify outdated, unsupported, or insecure software that could serve as an attack vector. - Implementation: Use inventory and vulnerability scanning tools to detect outdated versions and recommend secure alternatives. Configuration Audits: - Use Case: Evaluate system and network configurations to ensure secure settings (e.g., disabled SMBv1, enabled MFA). - Implementation: Implement automated configuration scanning tools like SCAP (Security Content Automation Protocol) to identify non-compliant systems. Network Audits: - Use Case: Examine network traffic, firewall rules, and endpoint communications to identify unauthorized or insecure connections. - Implementation: Utilize tools such as Wireshark, or Zeek to monitor and log suspicious network behavior. |
Обнаружение
Monitor email clients and applications for suspicious activity, such as missing messages or abnormal configuration and/or log entries.
On Windows systems, monitor for creation of suspicious inbox rules through the use of the New-InboxRule and Set-InboxRule PowerShell cmdlets.(Citation: Microsoft BEC Campaign) On MacOS systems, monitor for modifications to the RulesActiveState.plist, SyncedRules.plist, UnsyncedRules.plist, and MessageRules.plist files.(Citation: MacOS Email Rules)
Ссылки
- Niv Goldenberg. (2018, December 12). Rule your inbox with Microsoft Cloud App Security. Retrieved June 7, 2021.
- Microsoft. (n.d.). Set-InboxRule. Retrieved June 7, 2021.
- Microsoft. (n.d.). New-InboxRule. Retrieved June 7, 2021.
- Microsoft. (n.d.). Manage email messages by using rules. Retrieved June 11, 2021.
- Microsoft. (2023, February 22). Mail flow rules (transport rules) in Exchange Online. Retrieved March 13, 2023.
- Carr, N., Sellmer, S. (2021, June 14). Behind the scenes of business email compromise: Using cross-domain threat data to disrupt a large BEC campaign. Retrieved June 15, 2021.
- Apple. (n.d.). Use rules to manage emails you receive in Mail on Mac. Retrieved June 14, 2021.
- Microsoft. (2023, October 25). Octo Tempest crosses boundaries to facilitate extortion, encryption, and destruction. Retrieved March 18, 2024.
- Microsoft. (n.d.). Get-InboxRule. Retrieved June 10, 2021.
- Microsoft. (2023, February 22). Manage mail flow rules in Exchange Online. Retrieved March 13, 2023.
- Vengerik, B. et al.. (2014, December 5). Hacking the Street? FIN4 Likely Playing the Market. Retrieved December 17, 2018.
- Pany, D. & Hanley, C. (2023, May 3). Cloudy with a Chance of Bad Logs: Cloud Platform Log Configurations to Consider in Investigations. Retrieved October 16, 2023.
Связанные риски
Каталоги
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