SAML signature wrapping (XSW) → impersonate admin
Capture a legitimate SAML response. Re-arrange the XML so the IdP's signature still validates against the original assertion, but the SP parses an attacker-injected assertion claiming Admin.
§ Context
Assumed environment: target SP uses a SAML library susceptible to XSW (Java OpenSAML pre-3.4, python-saml older versions). Attacker has any low-priv SAML response to manipulate.
§ Steps
- 01Exfil sensitive dataExfiltrationT1041— Exfiltration Over C2 Channel
- 02Capture own SAML responseInitial AccessT1078— Valid Accounts
- 03POST modified response to SPLateral MovementT1550— Use Alternate Authentication Material
- 04SP parses attacker assertion → admin sessionPrivilege EscalationW-BFLA— Broken Function Level Authorization (API BFLA)
- 05Insert attacker assertion + restructure XMLCredential AccessAUTH-SAML-XSW— SAML Signature Wrapping (XSW)
§ References
§ Frequently asked
- What is the "SAML signature wrapping (XSW) → impersonate admin" attack path?
- Capture a legitimate SAML response. Re-arrange the XML so the IdP's signature still validates against the original assertion, but the SP parses an attacker-injected assertion claiming Admin. It chains 5 steps drawn from real-world offensive-security techniques.
- What starting position does this attack require?
- The first step is Exfil sensitive data (T1041) — a exfiltration primitive. Assumed environment: target SP uses a SAML library susceptible to XSW (Java OpenSAML pre-3.
- What is the final impact of this kill-chain?
- The final step lands on Insert attacker assertion + restructure XML (AUTH-SAML-XSW), which falls under Credential Access. From here, an operator typically pivots into post-exploitation or maintains persistence.
- How can defenders detect or prevent this attack?
- Detection and prevention vary per step. Refer to each linked MITRE ATT&CK entry under "References" — every technique on that page lists defensive controls, detection telemetry, and known threat-actor usage.
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