---
case_id: CASE-2026-1002
scenario: o365_suspicious_login
alert_type: azuread_legacy_auth_attempt
severity: medium
verdict: false_positive
source: soc-memory-poc
openviking_enriched: true
---

# CASE-2026-1002 Legacy protocol sign-in from unfamiliar IP blocked by policy

## 基本信息

- Case ID: CASE-2026-1002
- 标题: Legacy protocol sign-in from unfamiliar IP blocked by policy
- 告警类型: azuread_legacy_auth_attempt
- 来源系统: SOC Memory POC Mock Dataset
- 时间范围: 待补充
- 研判人 / Agent: AI Agent Draft
- 最终结论: 误报
- 严重等级: medium

## 告警摘要

Legacy authentication attempt from a cloud IP was blocked; investigation tied it to an approved migration tool test.

## 关键实体

- 用户: svc-migration@corp.example
- 主机: 无
- 邮箱: svc-migration@corp.example
- IP: 192.0.2.24
- 域名: 无
- 文件 Hash: 无
- 其他 IOC: 无

## 关键证据

- The account is a known migration service account.
- Source IP matched approved cloud migration vendor range.
- No successful sign-in occurred due to policy block.

## 研判过程摘要

1. 确认告警场景与核心风险：Legacy authentication attempt from a cloud IP was blocked; investigation tied it to an approved migration tool test.
2. 提取关键证据并交叉验证：The account is a known migration service account.
3. 对照关联 playbook / KB 复核告警模式与处置路径。
4. 基于关键证据与场景模式完成结论判定：误报。

## 结论依据

- 结论为误报。
- 最关键依据：The account is a known migration service account.
- 补充依据：Source IP matched approved cloud migration vendor range.

## 处置建议

- 记录误报原因，并更新检测例外或抑制条件。

## 可复用模式

- 命中模式: scenario:o365_suspicious_login, alert_type:azuread_legacy_auth_attempt
- 误报特征: 本案最终确认为误报，可用于补充抑制条件。
- 需关注的变体: 相关标签：o365, login, false-positive, legacy-auth

## 关联知识

- 关联 Playbook: [[PB-O365-LOGIN-001]]
- 关联 KB: [[KB-O365-LEGACY-AUTH]], [[KB-O365-IMPOSSIBLE-TRAVEL]]
- 关联历史 Case: [[CASE-2026-1001]], [[CASE-2026-1004]]
- 关联实体: [[svc-migration@corp.example]]

## 自动关联推荐

### 推荐历史 Case

- [[CASE-2026-1001]] (case score=0.651) This directory contains a structured security incident case report related to a high-severity event in an Office 365 environment, identified...
- [[CASE-2026-1004]] (case score=0.634) This directory contains a single incident case file related to a suspicious Microsoft 365 login attempt, identified as CASE-2026-1004. The c...

### 推荐知识条目

- [[KB-O365-IMPOSSIBLE-TRAVEL]] (knowledge score=0.626) This directory contains a knowledge base artifact focused on analyzing and validating Microsoft 365 impossible travel alerts—security events...
- [[PB-O365-LOGIN-001]] (knowledge score=0.61) This directory contains a security playbook focused on detecting and responding to suspicious Microsoft Entra ID sign-in activities within M...

## Lessons Learned

- 本案可沉淀为后续同类告警的快速判定参考。
- 若后续出现相同 lure、同类登录模式或相同关键证据，应优先联想本案与关联知识。

## 标签

- #case
- #scenario/o365_suspicious_login
- #alert/azuread_legacy_auth_attempt
- #verdict/false-positive
- #o365
- #login
- #false-positive
- #legacy-auth