Battle-Tested Incident Response Playbooks from Société Générale's CERT Team

Hook

When a Fortune 500 bank's security team responds to a breach, they don't improvise—they execute from a playbook refined through hundreds of real incidents. Now those playbooks are open source.

Context

Incident response is where security theory meets chaos. You're racing against an attacker who's already inside your network, your team is working across time zones, and every decision matters. The difference between a contained incident and a catastrophic breach often comes down to whether your team has a repeatable process they can execute under pressure.

The CERT teams at Société Générale and aDvens faced this reality constantly. Large financial institutions are high-value targets, experiencing everything from commodity malware to nation-state intrusions. Rather than reinventing their response process for each incident, they formalized their methodologies into structured cheat sheets—decision trees and action lists that guide responders from detection through remediation. In 2022, they released these Internal Response Methodologies (IRM) under Creative Commons, giving the security community access to procedures forged in one of the most threat-dense environments in enterprise security.

Technical Insight

The IRM repository structures incident response as a collection of methodology documents, each targeting a specific incident class. Unlike generic frameworks that describe what you should do conceptually, these are operational cheat sheets designed to be printed, posted on war room walls, or pulled up on a second monitor during active response.

The architecture is deliberately simple: PDF documents organized by incident type. This isn't a weakness—it's a design decision that prioritizes accessibility during crisis. When your team is responding to ransomware at 2 AM, you don't want to navigate a complex web application or database schema. You want a single-page reference that tells you exactly what to do next. The methodologies follow a consistent structure across incident types: initial triage questions, containment steps, evidence collection procedures, and remediation checklists.

What makes these methodologies valuable is their integration with established frameworks. They're built on SANS Institute foundations but adapted for operational reality. For example, a methodology might reference the standard incident response lifecycle (Preparation, Identification, Containment, Eradication, Recovery, Lessons Learned) but break containment into specific technical steps: "Isolate affected systems at network layer—disable switch ports or create firewall rules, do not power off unless dealing with memory-resident-only malware." This level of specificity comes from teams who've learned painful lessons about what works when milliseconds matter.

Consider how a typical response workflow might be documented. Rather than narrative text explaining the concept of evidence preservation, an IRM cheat sheet presents it as an executable checklist:

## Evidence Collection Priority Order

1. VOLATILE DATA (will be lost on reboot)
   □ Network connections: netstat -anob > network_state.txt
   □ Running processes: tasklist /v > processes.txt
   □ Logged-on users: qwinsta > active_users.txt
   □ Memory dump: Use winpmem/DumpIt to capture RAM
   
2. NON-VOLATILE DATA (persists after reboot)
   □ Disk imaging: Use write-blocker, prefer physical duplication
   □ Event logs: Copy Security, System, Application logs
   □ Prefetch files: C:\Windows\Prefetch\
   □ Registry hives: SYSTEM, SOFTWARE, SAM, SECURITY, NTUSER.DAT
   
3. TIMESTAMP PRESERVATION
   □ Document system time before collection
   □ Use forensic tools that preserve MAC times
   □ Hash all collected evidence: certutil -hashfile [file] SHA256

This format works because it maps directly to terminal commands and file paths. A junior analyst can execute it without deep forensics knowledge, while a senior responder can use it as a mental checklist to ensure nothing is missed during the chaos of an active incident.

The methodologies also embed decision logic directly into the procedures. Instead of separate documents for "malware incident" versus "targeted intrusion," a single methodology might include branching logic: "If indicators suggest automated/commodity malware, proceed to Section 3. If indicators suggest human operator (living-off-the-land techniques, lateral movement, credential dumping), escalate to targeted intrusion playbook and implement additional network segmentation immediately."

This approach reflects how actual incident response works. You start with limited information and make progressively refined decisions as you gather data. The IRM structure supports this by providing clear pivot points—moments where new evidence should change your response strategy. It's less like following a linear manual and more like traversing a decision tree where each branch represents a different threat model.

The integration with existing tools and frameworks is another architectural strength. The methodologies don't try to replace your SIEM, EDR platform, or ticketing system. Instead, they provide the cognitive framework that sits above those tools. A methodology might reference "check your EDR for process tree visualization" rather than prescribing a specific product. This tool-agnostic approach makes the methodologies portable across different security stacks while still providing concrete guidance.

Gotcha

The most significant limitation is temporal decay. These methodologies were published in 2022, which in security terms might as well be ancient history. Attack techniques evolve rapidly—living-off-the-land binaries (LOLBins) that weren't prevalent in 2022 are now standard adversary tradecraft, and cloud-native attack vectors have exploded in sophistication. The methodologies don't cover Kubernetes runtime attacks, serverless function abuse, or many of the supply chain compromise techniques that have emerged since publication. If you're responding to a modern cloud-native incident, you'll need to supplement heavily.

The documentation-only format is both a strength and a weakness. While PDFs are accessible during crises, they're also static. You can't integrate them into your SOAR platform, you can't track which steps were completed during an incident, and you can't customize them without creating maintenance headaches. If your organization has invested in incident response automation, these methodologies will feel like a step backward—you'll need to manually translate them into playbook automation. Additionally, because there's no active community or contribution mechanism visible in the repository, you're essentially getting a snapshot of 2022 best practices with no clear path to updates or community refinements.

Verdict

Use if: You're building or standardizing incident response processes for a SOC or CERT team, need proven frameworks to train junior analysts, or want to audit your existing procedures against battle-tested methodologies from a major financial institution. These cheat sheets are particularly valuable for organizations that prioritize process discipline over tool automation, or teams that respond to a wide variety of incident types and need quick-reference guides. Skip if: You're looking for automated playbooks that integrate with modern SOAR platforms, need cutting-edge guidance for cloud-native or container security incidents, or require actively maintained documentation that reflects 2024 threat landscapes. Also skip if you're already deeply committed to a specific framework like NIST 800-61 and don't have bandwidth to adapt external methodologies into your existing processes.