Cyberdudebivash

 Introduction

Server-Side Request Forgery (SSRF) occurs when an attacker tricks a vulnerable server into making unauthorized requests on their behalf. This often allows access to internal services, cloud metadata APIs, or even remote exploitation of internal networks.

At CyberDudeBivash, we call SSRF the “puppet master vulnerability” — because attackers manipulate servers to perform malicious actions as if the requests were trusted.

 How SSRF Works

1. Basic Attack
   • User input (like a URL) is used by the server to fetch data.
   • Attacker injects a crafted URL → server makes the malicious request.
   Example:https://victim.com/fetch?url=http://169.254.169.254/latest/meta-data/ (AWS metadata service access → leaking IAM credentials).
2. Blind SSRF
   • Attacker can’t see responses directly but infers success via time delays or side effects.
3. Advanced SSRF
   • Pivoting into internal admin panels, Redis/MongoDB services, or cloud resources.

 Real-World Impact

• Capital One Breach (2019)
  • SSRF exploited in AWS WAF → led to leakage of 100M+ records.
• Cloud Exploitation
  • Attackers abuse SSRF to steal IAM keys, escalate to full cloud takeover.
• Pivot to Internal Networks
  • SSRF can scan internal services (e.g., hitting http://localhost:8080/admin).
• Remote Code Execution (RCE)
  • In some cases, SSRF can be chained with deserialization flaws for full RCE.

 Detection & Threat Hunting

Indicators of SSRF Exploitation

• Server logs showing unexpected requests to internal/private IPs.
• Outbound traffic to unusual endpoints (127.0.0.1, 10.x.x.x, 169.254.x.x).
• Suspicious DNS lookups from the server host.

Threat Hunting Query (SIEM Example)

index=web_logs OR index=proxy_logs
| search "169.254." OR "localhost" OR "127.0.0.1" OR "internal"
| stats count by src_ip, uri, user

 Defense & Best Practices

1. Input Validation & Whitelisting
   • Allow only trusted and validated URLs/domains.
   • Block requests to internal/private IP ranges.
2. Metadata API Protection
   • In AWS, GCP, and Azure → enforce IMDSv2 / metadata protections.
3. Network Segmentation
   • Servers should not have unrestricted access to internal systems.
4. Least Privilege IAM Roles
   • Even if SSRF succeeds, limit damage by restricting server IAM permissions.
5. Timeouts & DNS Protections
   • Use short connection timeouts to prevent blind SSRF exploitation.
6. Web Application Firewalls (WAFs)
   • Block common SSRF payloads (169.254, localhost, private ranges).

 MITRE ATT&CK Mapping

• T1190 – Exploit Public-Facing Application
• T1078 – Valid Accounts (if stolen from metadata service)
• T1046 – Network Service Scanning (using SSRF for internal recon)

 Lessons Learned

• SSRF is one of the most devastating vulnerabilities because it abuses trusted servers as proxies for attackers.
• Cloud environments are especially high risk.
• Defense requires a combination of validation, IAM restrictions, network segmentation, and proactive monitoring.

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