Inside Société Générale's Incident Response Playbook: A CERT Team's Battle-Tested Methodologies

Hook

When a major European bank's security team open-sources their incident response playbooks, they're essentially giving you their crisis management handbook refined through years of defending billions in assets. But there's a catch: it's marked deprecated.

Context

In the chaos of a security incident, teams don't need theory—they need checklists. When ransomware encrypts your file servers at 2 AM or you discover unauthorized access to production databases, you need immediate, actionable steps, not a 200-page framework document. This is the problem CERT Societe Generale tackled when they created the Incident Response Methodologies (IRM) repository.

Before structured incident response methodologies became standard, security teams often improvised during crises, leading to missed forensic evidence, incomplete containment, and inconsistent documentation. While frameworks like NIST SP 800-61 provide comprehensive guidance, they're not designed for the frantic pace of active incidents. CERT Societe Generale, the Computer Emergency Response Team for one of Europe's largest banking groups, distilled their real-world experience into tactical cheat sheets—one-page documents focused on specific incident types. Released under Creative Commons licensing, these materials represented a rare glimpse into enterprise-grade incident response from a team defending critical financial infrastructure. The 'deprecated' tag in the repository name signals this resource is no longer actively maintained, but the fundamental approaches remain instructive for teams building their own IR capabilities.

Technical Insight

The IRM repository's architecture is deliberately anti-framework. Rather than prescribing a universal methodology, it provides discrete, incident-specific playbooks organized by attack vector and impact type. Each IRM document follows a consistent structure: initial triage questions, technical indicators to collect, containment steps, eradication procedures, and recovery guidance. This modular approach means responders can grab the relevant cheat sheet without navigating complex documentation hierarchies.

The repository's organization reflects how CERTs actually work. Documents are categorized by incident taxonomy—phishing campaigns, malware infections, data exfiltration, denial of service, insider threats, and physical security breaches. For example, the malware incident response methodology doesn't just say "isolate the system." It provides a decision tree: Is the malware ransomware? Check for file encryption patterns and ransom notes. Is it a banking trojan? Look for web injection artifacts and credential harvesting. Each branch leads to specific technical actions.

Here's what a simplified version of their approach might look like in practice. If you were implementing an automated triage system based on their methodologies, you might structure it like this:

class IRMPlaybook:
    def __init__(self, incident_type):
        self.incident_type = incident_type
        self.evidence_collected = []
        self.containment_actions = []
    
    def triage_malware_incident(self, indicators):
        """
        Based on IRM malware response methodology
        """
        findings = {
            'severity': 'unknown',
            'recommended_actions': []
        }
        
        # Initial triage questions from IRM approach
        if indicators.get('ransomware_note') or indicators.get('encrypted_files'):
            findings['severity'] = 'critical'
            findings['recommended_actions'] = [
                'DO NOT REBOOT - preserve memory artifacts',
                'Isolate affected systems from network immediately',
                'Identify patient zero and propagation path',
                'Check backup integrity before containment',
                'Document ransom note and bitcoin addresses'
            ]
            self.collect_memory_dump()
            self.snapshot_network_connections()
        
        elif indicators.get('c2_communication'):
            findings['severity'] = 'high'
            findings['recommended_actions'] = [
                'Capture network traffic to C2 servers',
                'Identify all beaconing hosts via netflow',
                'Extract C2 domains/IPs for blocking',
                'Perform process memory analysis',
                'Check for lateral movement artifacts'
            ]
            self.capture_network_traffic()
        
        return findings
    
    def collect_memory_dump(self):
        # IRM emphasizes volatile data collection
        self.evidence_collected.append({
            'type': 'memory',
            'timestamp': datetime.now(),
            'priority': 'critical'
        })
    
    def snapshot_network_connections(self):
        # Preserve network state before containment
        self.evidence_collected.append({
            'type': 'network_connections',
            'data': 'netstat output, active connections',
            'note': 'Collected before isolation'
        })

What makes the IRM approach valuable is its emphasis on evidence preservation before containment. Many incident response procedures prioritize stopping the attack, potentially destroying forensic artifacts in the process. The Société Générale methodologies explicitly call out this sequencing: capture volatile data first, then contain. For memory-resident malware or fileless attacks, this ordering is crucial.

The repository also demonstrates pragmatic tooling recommendations. Rather than prescribing expensive commercial tools, the methodologies assume responders will use whatever is available—built-in OS utilities, open-source forensic tools, or commercial platforms. The cheat sheets focus on what data to collect, not which vendor product to use. This tool-agnostic approach has aged well; the collection priorities remain valid even as specific tools evolve.

Another architectural decision worth noting: multilingual documentation. The IRMs are available in English, Russian, and Spanish, reflecting Société Générale's global operations. This isn't just translation—each language version is maintained separately, suggesting these were actually used by regional CERT teams. For organizations with international security operations, this structure provides a template for how to scale incident response documentation across language barriers.

The deprecated status likely reflects a shift in how the team maintains this knowledge. Many organizations have moved from static documentation to dynamic runbook systems integrated with SOAR (Security Orchestration, Automation, and Response) platforms. The IRM repository represents a snapshot of pre-SOAR incident response—still valid in its fundamentals, but predating the automation layer most enterprises have now added.

Gotcha

The elephant in the room is that 'deprecated' tag. While the repository documentation doesn't explain why it was deprecated or point to a successor, this creates real risk for teams adopting these methodologies wholesale. Threat landscapes shift rapidly—tactics that worked five years ago may miss modern attack techniques like supply chain compromises, cloud-native attacks, or AI-assisted social engineering. The malware IRM, for instance, predates widespread cryptocurrency mining malware and may not address containerized malware deployment. Without maintenance, these playbooks become increasingly historical rather than operational.

There's also the context problem: these methodologies were developed for a specific organizational structure—a European financial institution with presumably mature security operations, dedicated CERT staff, and established legal/regulatory frameworks. Smaller organizations or teams in different regulatory environments may find assumptions baked into the IRMs that don't translate. The playbooks assume access to network visibility tools, endpoint forensic capabilities, and the authority to isolate systems immediately. Startups running entirely in cloud environments with microservices architectures will need significant adaptation. The documentation is also entirely text-based with no workflow automation examples, meaning you'll need to manually translate these into whatever runbook or SOAR system your organization uses.

Verdict

Use if: You're building incident response capabilities from scratch and need proven templates to bootstrap your playbooks, especially if you're in financial services or regulated industries where Société Générale's context is relevant. These IRMs excel as training materials for junior SOC analysts learning incident response fundamentals—the clear structure and decision trees provide excellent pedagogical value. They're also valuable for security teams performing gap analysis against their existing procedures; comparing your playbooks against a major bank's approach can reveal blind spots. Skip if: You need actively maintained, current threat intelligence or methodologies that address modern attack patterns like cloud-native breaches, Kubernetes compromises, or supply chain attacks. The deprecated status means you're inheriting technical debt if you adopt these without significant updates. Also skip if you operate primarily in cloud environments—these playbooks assume traditional network/endpoint visibility that may not apply to serverless or containerized architectures. For actively maintained alternatives, look to NIST SP 800-61 Rev 2, the SANS Incident Handler's Handbook, or consider modern platforms like TheHive that combine playbooks with case management tooling.