DFIR in Practice: Responding to Ransomware and Non-Ransomware Breaches Before and After Encryption

DFIR RESPONSE AFTER RANSOMWARE DEPLOYMENT

Scenario: Encryption has occurred, ransom note is present

DFIR RESPONSE BEFORE RANSOMWARE DEPLOYMENT

Scenario: Breach detected, no encryption yet

This is the most valuable moment in DFIR: the chance to stop ransomware before it detonates.

Threat Hunting Is Essential in DFIR

DFIR does not end with containment or recovery. Threat hunting is a critical, continuous activity during and after DFIR, especially in ransomware cases.

Attackers rarely leave only one foothold.

Why threat hunting matters here

• Ransomware operators often deploy multiple persistence mechanisms
• Backup access and identity abuse may not be immediately visible
• Secondary access paths are commonly planted as insurance
• Detection gaps are frequently exploited repeatedly

Threat hunting turns assumptions into evidence.

Practical Threat Hunting Focus Areas

Identity and Access

• Hunt for abnormal admin logons outside business hours
• Identify service accounts used interactively
• Look for token abuse, stale sessions, and unusual delegation

Lateral Movement

• Search for abnormal SMB, RDP, WinRM, and PsExec usage
• Correlate remote execution with credential changes
• Identify hosts acting as unexpected pivots

Persistence

• Scheduled tasks with vague names
• Services running under high-privilege accounts
• Startup scripts or GPO changes
• OAuth apps, API keys, or cloud roles added quietly

Defense Evasion

• Disabled logging or EDR tampering
• Cleared event logs
• Unexpected exclusions added to security tools

Example Threat Hunting Hypotheses

• A compromised admin account was used from multiple hosts in a short time window
• An attacker created persistence before ransomware execution as a fallback
• Backup systems were enumerated or accessed prior to encryption
• A second access method exists outside the original intrusion vector
• Cloud or identity artifacts outlived on-prem remediation

Each hypothesis should be tested with logs, telemetry, and timelines.

Threat Actor Identification and Playbook Awareness

One critical element that runs through both DFIR scenarios, before and after ransomware deployment, is identifying the threat actor or threat group behind the intrusion.

This is not about attribution for publicity.
It is about understanding behavior.

Why threat actor identification matters

Different ransomware operators follow distinct playbooks. Knowing who you are dealing with helps answer questions such as:

• Do they typically exfiltrate data before encryption?
• Do they deploy multiple persistence mechanisms?
• Do they reattack the same victim weeks later?
• Do they favor identity abuse, VPN compromise, or exploited vulnerabilities?
• Do they target backups early?
• Do they commonly leave secondary access paths?

Threat actor awareness allows DFIR teams to anticipate what may already be in place, even if it has not yet been discovered.

What threat actor identification looks like in practice

In real DFIR work, identification is usually probabilistic, not absolute.

Indicators commonly used include:

• Ransom note structure and language
• Encryption method and file extensions
• Tooling used for lateral movement and deployment
• Infrastructure patterns and execution timing
• TTP alignment with known campaigns

This information is correlated with:

• Observed attacker behavior
• Timeline reconstruction
• Known ransomware operations and intrusion patterns

The result is often a high-confidence behavioral match, not a definitive name.

That is usually enough.

Using threat actor playbooks defensively

Once a likely threat actor profile is identified, DFIR teams should immediately ask:

• What persistence techniques does this actor commonly use?
• What secondary access methods do they favor?
• How do they typically escalate privileges?
• Do they commonly target cloud or identity platforms?
• Do they deploy wipers or delayed encryption?
• What post-encryption activity is common for them?

This informs targeted threat hunting.

Instead of hunting blindly, you hunt what this actor is known to do.

Examples:

• Hunting for specific persistence patterns
• Reviewing identity abuse consistent with that group
• Inspecting backup systems if the actor is known to target them early
• Extending monitoring windows if reentry is common

Managing expectations around attribution

It is important to communicate clearly with stakeholders:

• Threat actor identification supports response strategy
• It does not guarantee full visibility
• It does not eliminate the need for broad hunting
• It does not replace evidence-based decisions

Attribution informs prioritization, not certainty.

Strategic DFIR takeaway

Threat actor identification allows DFIR teams to:

• Anticipate attacker behavior
• Apply known playbooks defensively
• Focus threat hunting where it matters most
• Reduce uncertainty faster
• Make more informed containment and recovery decisions

In ransomware DFIR, understanding who you are dealing with often answers what to look for next.

Working With Unfamiliar Clients and Threat Hunting Tooling

In many DFIR engagements, especially ransomware cases, you are responding for a client you do not know well. Their security maturity, visibility, and tooling are often unclear at the start of the incident.

Because of this, an early and explicit discussion about what tools already exist is essential before conducting effective threat hunting.

Key questions to ask early

• What endpoint protection or EDR is deployed today?
• Is it deployed everywhere or only on a subset of systems?
• What identity platform is in use and what logs are retained?
• What network telemetry exists firewall, VPN, proxy, NDR?
• What cloud audit logs are enabled and for how long?
• Is there a SIEM or central log aggregation?
• Do we have immediate access to raw telemetry?

Threat hunting is constrained by visibility. Understanding these limits early prevents false confidence.

Using existing tools first

In real-world DFIR, it is almost always better to hunt using tools that are already present rather than attempting to deploy new tooling mid-incident. Even partial or imperfect telemetry can reveal:

• Identity abuse
• Lateral movement
• Persistence mechanisms
• Secondary access paths

The objective is to extract maximum value from what already exists.

When adequate tools do not exist

In some environments, threat hunting tools are minimal or nonexistent. This is common in smaller organizations or legacy infrastructures. When visibility is insufficient, DFIR must shift strategy.

Real-world recommended actions include:

• Manual log collection from critical systems
• Increasing native logging where safe to do so
• Focusing heavily on identity containment
• Aggressive credential resets
• Rebuilding high-risk systems rather than trusting them
• Assuming blind spots and reducing risk structurally

When you cannot hunt with confidence, you compensate with containment, rebuilds, and hardening.

Managing expectations

It is critical to communicate clearly with the client:

• What can be hunted with current visibility
• What cannot be conclusively validated
• What assumptions must be made
• What residual risk remains

Professional DFIR acknowledges limitations instead of hiding them.

Not All Breaches End in Encryption or Deep Intrusion

One of the most common misconceptions in incident response is that every breach follows a long, complex kill chain that ends in ransomware or deep internal compromise.

In reality, many breaches are far simpler and just as damaging.

In some cases, an attacker exploits a single externally reachable vulnerability, gains access to a system, and immediately begins data exfiltration without deploying ransomware, moving laterally, or establishing long-term persistence.

When this happens, the DFIR objective shifts.

The task is no longer only to hunt for internal attacker activity, but to identify what was exploitable from an external point of view and what data was exposed as a result.

Why This Scenario Is Common

This pattern is frequently seen when:

• Internet-facing applications are vulnerable
• VPNs, gateways, or appliances are unpatched
• Authentication bypass or file disclosure flaws exist
• Cloud services are misconfigured
• Monitoring of egress traffic is limited

In these cases, attackers often:

• Access data directly
• Exfiltrate at scale
• Leave minimal artifacts
• Never deploy malware
• Never trigger ransomware

The absence of encryption does not mean the absence of impact.

DFIR Focus in Externally Exploitable Breaches

When responding to this type of incident, DFIR must focus on exposure analysis, not just internal compromise.

Key questions include:

• What systems are exposed to the internet?
• What vulnerabilities were present at the time of access?
• Were authentication controls bypassed?
• What data could be accessed without lateral movement?
• What outbound connections occurred from exposed systems?

This often requires reconstructing the external attack surface as it existed during the breach, not as it exists today.

Practical Actions for External Exposure Analysis

Real-world DFIR actions in these cases include:

• Identifying all internet-facing assets
• Reviewing patch levels at the time of compromise
• Validating known exploited vulnerabilities
• Reviewing application and access logs
• Analyzing outbound traffic for exfiltration patterns
• Determining what data was accessible from the exposed service

The goal is to answer two critical questions:

• What was exploitable?
• What was exposed?

Threat Hunting From an External Perspective

Threat hunting in this scenario extends beyond internal telemetry.

Effective hunting focuses on:

• Historical exposure of services and endpoints
• Evidence of automated exploitation
• Repeated access patterns from external sources
• Large or anomalous data transfers
• API misuse or abuse

This type of hunting often uncovers breaches that never triggered internal alarms.

Strategic DFIR Takeaway

Not every incident escalates to ransomware.
Not every attacker needs persistence.

Sometimes the attacker’s goal is simple: access data and leave.

DFIR must be prepared to:

• Analyze external exposure
• Understand what was exploitable
• Quantify data impact
• Close the vulnerability permanently

Whether the attacker encrypts systems or silently exfiltrates data, the objective remains the same:

Reduce exposure, eliminate the weakness, and ensure the same path cannot be used again.

Where Pentesting Fits in This Scenario

In breaches driven by externally exploitable vulnerabilities and data exfiltration, this is also where offensive security skills, including penetration testing, become highly relevant.

Not as a replacement for DFIR, but as a complement.

Why pentesting skills matter here

When the attacker does not deploy malware, move laterally, or establish deep persistence, DFIR alone may not fully explain how access was possible from the outside.

People with pentesting and adversarial skills are often well suited to:

• Identify externally exploitable vulnerabilities
• Reproduce attack paths safely
• Validate whether exploitation is still possible
• Confirm what an attacker could realistically access
• Think from the attacker’s point of view rather than the defender’s

This perspective is critical when the breach hinges on exposure rather than intrusion depth.

Important distinction: DFIR vs Pentesting

It is important to be clear about roles.

DFIR focuses on what actually happened
Evidence, timelines, impact, and response

Pentesting focuses on what could be exploited
Exposure, attack paths, and validation

In vulnerability-driven breaches, both perspectives are necessary:

• DFIR determines what data was accessed or exfiltrated
• Pentesting techniques help confirm how it was accessed and whether the weakness still exists

Real-world DFIR use of pentesting techniques

In practice, DFIR teams often apply pentesting-style methods, even if the engagement is not formally a pentest.

Examples include:

• Safely reproducing an exploit against a test system
• Validating authentication bypasses
• Confirming file or API exposure
• Enumerating attack surface as the attacker saw it
• Testing whether fixes actually close the path

This is done carefully, under change control, and with clear scope.

Strategic takeaway

When breaches rely on external exposure rather than internal compromise, DFIR benefits significantly from offensive security thinking.

Pentesting skills help answer:

• Was this exploitable from the internet?
• Could it have been exploited at scale?
• Is it truly fixed now?
• Could another attacker repeat this tomorrow?

Used correctly, pentesting does not blur DFIR.
It strengthens it, especially in data theft cases where the attacker never needed ransomware at all.

Tip: Using a Dedicated DFIR Virtual Machine During an Incident

When a DFIR professional accesses a client’s network, monitoring tools, or forensic data during an incident, the default and recommended approach is to use a dedicated DFIR virtual machine.

This is not an operational preference.
It is a security, integrity, and defensibility requirement.

Why a Dedicated DFIR VM Matters

During an incident, the environment must be treated as hostile by default.
Credentials, tooling, and access paths may already be compromised.

Using a dedicated DFIR VM provides:

• Isolation from potentially malicious client systems
• Protection against credential harvesting and lateral abuse
• Separation of client data from personal or corporate environments
• Reduced risk of cross-contamination between engagements

A DFIR responder should never access a compromised environment from their primary workstation.

Evidence Integrity and Defensibility

DFIR work often becomes subject to:

• Legal review
• Insurance claims
• Regulatory reporting
• External audits

A dedicated VM helps ensure:

• Clear separation of evidence
• Controlled tooling and configurations
• Reduced risk of accidental modification
• A defensible investigation process

This becomes critical if findings are later challenged.

Credential Hygiene and Access Control

Incident response frequently involves:

• Temporary high-privilege access
• Break-glass credentials
• Sensitive console access

A DFIR VM allows:

• Client-specific credential storage
• Clean teardown after the engagement
• No reuse of credentials across clients

Once the incident concludes, the VM can be destroyed or archived securely.

Tooling Control and Repeatability

DFIR VMs are typically preconfigured with:

• Approved forensic and analysis tools
• Known versions and configurations
• Time synchronization and hashing utilities
• Logging or session recording where required

This supports consistent workflows, peer review, and reliable outcomes.

When Exceptions May Apply

There are limited scenarios where a full DFIR VM may not be used:

• Read-only access to a web portal from a hardened workstation
• Client-provided jump hosts or VDI environments
• Time-critical situations where isolation tooling is temporarily unavailable

Even in these cases:

• Privileges should be minimal
• Credentials should not be cached
• Actions should be logged

These are exceptions, not standard practice.

DFIR Best Practice Summary

When accessing:

• SIEM platforms
• EDR consoles
• Cloud administration portals
• Identity systems
• Forensic artifacts

A dedicated DFIR VM should be used.

It protects the responder, the client, and the integrity of the investigation.

Practical Takeaway

Using a DFIR VM is not about convenience or habit.
It is about reducing risk, maintaining trust, and ensuring the response itself does not become part of the problem.

A disciplined DFIR process includes disciplined access.

DFIR Real-World Principles

• Identity is the primary attack vector
• Ransomware is the final phase, not the breach
• Backups are targeted early
• Stealth matters before encryption
• Evidence enables confidence

Final Goal of DFIR

The goal of DFIR is not just recovery.

The goal is to make the threat actor’s life harder while:

• Detecting and removing what they planted
• Identifying vulnerabilities they exploited
• Closing paths they abused
• Increasing uncertainty, friction, and risk for the attacker

Every credential reset, every persistence mechanism removed, every control hardened contributes to denying the attacker confidence, both now and in future attempts.

A successful DFIR engagement does not just end an incident. It ensures the attacker never has the same easy path again.