security protocol_error ai_generated true

SAML XML签名包装攻击绕过签名验证

SAML XML signature wrapping attack bypasses signature validation

ID: security/saml-xml-signature-wrapping

其他格式: JSON · Markdown 中文 · English
85%修复率
87%置信度
1证据数
2023-11-05首次发现

版本兼容性

版本状态引入弃用备注
SAML 2.0 active — — —
Shibboleth IdP 4.3.0 active — — —
Okta 2024.01.0 active — — —
OpenSAML 4.3.0 active — — —

根因分析

SAML响应包含多个断言，但XML签名仅覆盖一个良性的断言；攻击者插入一个未签名的恶意断言，由于宽松的XML解析逻辑而被应用程序处理。

English

The SAML response contains multiple assertions, but the XML signature only covers a benign assertion; the attacker inserts a malicious assertion that is not signed but is processed by the application due to lax XML parsing logic.

generic

官方文档

https://wiki.shibboleth.net/confluence/display/OSAML/XML+Signature+Wrapping+Attack

解决方案

  1. 强制只处理SAML响应中的第一个（或单个）断言，并且它必须是签名覆盖的那个。Java中使用OpenSAML的示例：if (response.getAssertions().size() != 1) throw new SecurityException('不允许有多个断言');
  2. 使用严格的XML模式验证，拒绝SAML响应中任何意外的元素或结构变化。

无效尝试

常见但无效的做法:

  1. Only validating the signature on the first assertion in the response 90% 失败

    Attackers can reorder assertions or place the signed assertion anywhere; the application may process a later unsigned assertion.

  2. Using a DOM parser without disabling external entity processing 95% 失败

    This doesn't address signature wrapping; the parser still sees all assertions, and signature validation is not enforced on each.