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  1. Frameworks
  2. >ATTACK
  3. >Collection
  4. >ATTACK-T1114.003
ATTACK-T1114.003Active

Email Forwarding Rule

Statement

Adversaries may setup email forwarding rules to collect sensitive information. Adversaries may abuse email forwarding rules to monitor the activities of a victim, steal information, and further gain intelligence on the victim or the victim’s organization to use as part of further exploits or operations.(Citation: US-CERT TA18-068A 2018) Furthermore, email forwarding rules can allow adversaries to maintain persistent access to victim's emails even after compromised credentials are reset by administrators.(Citation: Pfammatter - Hidden Inbox Rules) Most email clients allow users to create inbox rules for various email functions, including forwarding to a different recipient. These rules may be created through a local email application, a web interface, or by command-line interface. Messages can be forwarded to internal or external recipients, and there are no restrictions limiting the extent of this rule. Administrators may also create forwarding rules for user accounts with the same considerations and outcomes.(Citation: Microsoft Tim McMichael Exchange Mail Forwarding 2)(Citation: Mac Forwarding Rules)

Any user or administrator within the organization (or adversary with valid credentials) can create rules to automatically forward all received messages to another recipient, forward emails to different locations based on the sender, and more. Adversaries may also hide the rule by making use of the Microsoft Messaging API (MAPI) to modify the rule properties, making it hidden and not visible from Outlook, OWA or most Exchange Administration tools.(Citation: Pfammatter - Hidden Inbox Rules)

In some environments, administrators may be able to enable email forwarding 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 enable forwarding on all or specific mail an organization receives.

Location

Tactic
Collection

Technique Details

Identifier
ATTACK-T1114.003
Parent Technique
ATTACK-T1114
ATT&CK Page
View on MITRE

Tactics

Collection

Platforms

LinuxmacOSOffice SuiteWindows

Detection

Email Forwarding Rule Abuse Detection Across Platforms

Mitigations

Disable or Remove Feature or Program: Disable or remove unnecessary and potentially vulnerable software, features, or services to reduce the attack surface and prevent abuse by adversaries. This involves identifying software or features that are no longer needed or that could be exploited and ensuring they are either removed or properly disabled. This mitigation can be implemented through the following measures:

Remove Legacy Software:

  • Use Case: Disable or remove older versions of software that no longer receive updates or security patches (e.g., legacy Java, Adobe Flash).
  • Implementation: A company removes Flash Player from all employee systems after it has reached its end-of-life date.

Disable Unused Features:

  • Use Case: Turn off unnecessary operating system features like SMBv1, Telnet, or RDP if they are not required.
  • Implementation: Disable SMBv1 in a Windows environment to mitigate vulnerabilities like EternalBlue.

Control Applications Installed by Users:

  • Use Case: Prevent users from installing unauthorized software via group policies or other management tools.
  • Implementation: Block user installations of unauthorized file-sharing applications (e.g., BitTorrent clients) in an enterprise environment.

Remove Unnecessary Services:

  • Use Case: Identify and disable unnecessary default services running on endpoints, servers, or network devices.
  • Implementation: Disable unused administrative shares (e.g., C$, ADMIN$) on workstations.

Restrict Add-ons and Plugins:

  • Use Case: Remove or disable browser plugins and add-ons that are not needed for business purposes.
  • Implementation: Disable Java and ActiveX plugins in web browsers to prevent drive-by attacks.

Encrypt Sensitive Information: Protect sensitive information at rest, in transit, and during processing by using strong encryption algorithms. Encryption ensures the confidentiality and integrity of data, preventing unauthorized access or tampering. This mitigation can be implemented through the following measures:

Encrypt Data at Rest:

  • Use Case: Use full-disk encryption or file-level encryption to secure sensitive data stored on devices.
  • Implementation: Implement BitLocker for Windows systems or FileVault for macOS devices to encrypt hard drives.

Encrypt Data in Transit:

  • Use Case: Use secure communication protocols (e.g., TLS, HTTPS) to encrypt sensitive data as it travels over networks.
  • Implementation: Enable HTTPS for all web applications and configure mail servers to enforce STARTTLS for email encryption.

Encrypt Backups:

  • Use Case: Ensure that backup data is encrypted both during storage and transfer to prevent unauthorized access.
  • Implementation: Encrypt cloud backups using AES-256 before uploading them to Amazon S3 or Google Cloud.

Encrypt Application Secrets:

  • Use Case: Store sensitive credentials, API keys, and configuration files in encrypted vaults.
  • Implementation: Use HashiCorp Vault or AWS Secrets Manager to manage and encrypt secrets.

Database Encryption:

  • Use Case: Enable Transparent Data Encryption (TDE) or column-level encryption in database management systems.
  • Implementation: Use MySQL’s built-in encryption features to encrypt sensitive database fields such as social security numbers.

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.

Out-of-Band Communications Channel: Establish secure out-of-band communication channels to ensure the continuity of critical communications during security incidents, data integrity attacks, or in-network communication failures. Out-of-band communication refers to using an alternative, separate communication path that is not dependent on the potentially compromised primary network infrastructure. This method can include secure messaging apps, encrypted phone lines, satellite communications, or dedicated emergency communication systems. Leveraging these alternative channels reduces the risk of adversaries intercepting, disrupting, or tampering with sensitive communications and helps coordinate an effective incident response.(Citation: TrustedSec OOB Communications)(Citation: NIST Special Publication 800-53 Revision 5)

SP 800-53
SP800-53-AC-16relatedvia ctid-attack-to-sp800-53
SP800-53-AC-17relatedvia ctid-attack-to-sp800-53
SP800-53-AC-19relatedvia ctid-attack-to-sp800-53
SP800-53-AC-20relatedvia ctid-attack-to-sp800-53
SP800-53-AC-4relatedvia ctid-attack-to-sp800-53
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Collection36 controls
ATTACK-T1005Data from Local SystemATTACK-T1025Data from Removable MediaATTACK-T1039Data from Network Shared DriveATTACK-T1056Input CaptureATTACK-T1056.001KeyloggingATTACK-T1056.002GUI Input CaptureATTACK-T1056.003Web Portal CaptureATTACK-T1056.004Credential API HookingATTACK-T1074Data StagedATTACK-T1074.001Local Data StagingATTACK-T1074.002Remote Data StagingATTACK-T1113Screen CaptureATTACK-T1114Email CollectionATTACK-T1114.001Local Email CollectionATTACK-T1114.002Remote Email CollectionATTACK-T1114.003Email Forwarding RuleATTACK-T1115Clipboard DataATTACK-T1119Automated CollectionATTACK-T1123Audio CaptureATTACK-T1125Video CaptureATTACK-T1185Browser Session HijackingATTACK-T1213Data from Information RepositoriesATTACK-T1213.001ConfluenceATTACK-T1213.002SharepointATTACK-T1213.003Code RepositoriesATTACK-T1213.004Customer Relationship Management SoftwareATTACK-T1213.005Messaging ApplicationsATTACK-T1213.006DatabasesATTACK-T1530Data from Cloud StorageATTACK-T1560Archive Collected DataATTACK-T1560.001Archive via UtilityATTACK-T1560.002Archive via LibraryATTACK-T1560.003Archive via Custom MethodATTACK-T1602Data from Configuration RepositoryATTACK-T1602.001SNMP (MIB Dump)ATTACK-T1602.002Network Device Configuration Dump