Phishing for Information: Spearphishing Attachment

Adversaries may send spearphishing messages with a malicious attachment to elicit sensitive information that can be used during targeting. Spearphishing for information is an attempt to trick targets into divulging information, frequently credentials or other actionable information. Spearphishing for information frequently involves social engineering techniques, such as posing as a source with a reason to collect information (ex: Establish Accounts or Compromise Accounts) and/or sending multiple, seemingly urgent messages.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email and usually rely upon the recipient populating information then returning the file.[1][2] The text of the spearphishing email usually tries to give a plausible reason why the file should be filled-in, such as a request for information from a business associate. Adversaries may also use information from previous reconnaissance efforts (ex: Search Open Websites/Domains or Search Victim-Owned Websites) to craft persuasive and believable lures.

ID: T1598.002
Sub-technique of:  T1598
Tactic: Reconnaissance
Platforms: PRE
Contributors: Philip Winther; Robert Simmons, @MalwareUtkonos; Sebastian Salla, McAfee
Version: 1.1
Created: 02 October 2020
Last Modified: 15 April 2021

Procedure Examples

ID Name Description
G0035 Dragonfly

Dragonfly has used spearphishing with Microsoft Office attachments to enable harvesting of user credentials.[3]

G1008 SideCopy

SideCopy has crafted generic lures for spam campaigns to collect emails and credentials for targeting efforts.[4]

G0121 Sidewinder

Sidewinder has sent e-mails with malicious attachments that lead victims to credential harvesting websites.[5][6][7]

Mitigations

ID Mitigation Description
M1054 Software Configuration

Use anti-spoofing and email authentication mechanisms to filter messages based on validity checks of the sender domain (using SPF) and integrity of messages (using DKIM). Enabling these mechanisms within an organization (through policies such as DMARC) may enable recipients (intra-org and cross domain) to perform similar message filtering and validation.[8][9]

M1017 User Training

Users can be trained to identify social engineering techniques and spearphishing attempts.

Detection

ID Data Source Data Component Detects
DS0015 Application Log Application Log Content

Monitor for suspicious email activity, such as numerous accounts receiving messages from a single unusual/unknown sender. Filtering based on DKIM+SPF or header analysis can help detect when the email sender is spoofed.[8][9]

DS0029 Network Traffic Network Traffic Content

Monitor and analyze traffic patterns and packet inspection associated to protocol(s) that do not follow the expected protocol standards and traffic flows (e.g extraneous packets that do not belong to established flows, gratuitous or anomalous traffic patterns, anomalous syntax, or structure). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g. monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).

Network Traffic Flow

Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.

References