Equifax · 2017 · Credit reporting
~147 million individualsUnpatched internet-facing application (CVE-2017-5638, Apache Struts)
A known, publicly disclosed Struts deserialization flaw remained unpatched on an internet-facing dispute portal for roughly two months after a fix was available. Attackers used it to gain a foothold, then moved through the network largely undetected for 76 days. An expired certificate on a traffic-inspection device meant the exfiltration traffic went unexamined for months.
The chain
- 01Exploitation of an unpatched public-facing application
- 02Discovery of unencrypted credentials stored on the compromised host
- 03Lateral movement into databases that shared no network segmentation boundary
- 04Staged exfiltration over encrypted channels that inspection tooling could not read
T1190 Exploit Public-Facing ApplicationT1552.001 Credentials In FilesT1210 Exploitation of Remote ServicesT1041 Exfiltration Over C2 Channel
The lesson
The initial vulnerability was ordinary and the patch existed. What turned it into one of the largest breaches on record was flat internal networking, credentials in plaintext on disk, and a monitoring control that had silently failed and that nobody noticed.
What we test for
Whether a single compromised web host actually reaches your data stores, and whether your inspection and alerting controls are functioning rather than merely deployed.