# Deserialization of Untrusted Data (CWE-502)

The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

**Stack:** Go

- Prevalence: 中 覆盖 3 种语言
- Impact: 关键 3 条严重级别为关键的规则
- Prevention: 已记录 7 个修复示例

**OWASP:** Software and Data Integrity Failures (A08:2021-Software and Data Integrity Failures) - #8

## Description

Many programming languages allow the serialization of objects for storage or transmission. When untrusted data is deserialized, it can lead to code execution, denial of service, or other unintended consequences.

## Prevention

基于 2 条 Shoulder 检测规则的 Deserialization of Untrusted Data 预防策略。

### Go

Use strict typed structs instead of interface{} and avoid gob with untrusted data

Validate all training data against strict schemas and apply content moderation before ingestion

## Warning Signs

- [HIGH] Untrusted data is deserialized without validation
- [HIGH] truly dangerous deserialization in Go
- [HIGH] Untrusted data flows to ... without validation
- [HIGH] untrusted data flowing into AI/LLM fine-tuning or training processes without validation

## Consequences

- 执行未授权代码
- 拒绝服务 (DoS):崩溃/退出/重启
- 修改应用程序数据

## Mitigations

- 尽可能避免对不可信数据进行反序列化
- 如果必须反序列化,使用 JSON 等更安全的格式
- 实施数字签名等完整性校验
- 在低权限环境中隔离反序列化操作

## Detection

- Total rules: 7
- Critical: 3
- Languages: go, javascript, typescript, python

## Rules by Language

### Go (2 rules)

- **Insecure Deserialization** [HIGH]: Detects truly dangerous deserialization in Go. Unlike Java or Python, Go's encoding/json
is safe (data-only parsing, no code execution). This rule focuses on:
- gob.Decoder: Can instantiate arbitrary types, potential RCE (CRITICAL)
- json/yaml/xml to interface{}: Type confusion risk when combined with untrusted input (MEDIUM)

Note: json.Unmarshal to typed structs is NOT flagged as it cannot execute code.
  - Remediation: Use strict struct types instead of interface{} and validate after unmarshaling.

```go
type User struct {
    Name  string `json:"name"`
    Email string `json:"email"`
}

var user User
if err := json.Unmarshal(input, &user); err != nil {
    return err
}
```

Learn more: https://shoulder.dev/learn/go/cwe-502/unsafe-deserialization
- **LLM Training Data Poisoning** [HIGH]: Detects untrusted data flowing into AI/LLM fine-tuning or training processes without validation.
  - Remediation: Validate all training data against strict schemas before ingestion.

```go
if err := validate.Struct(doc); err != nil {
    return errors.New("validation failed")
}
```

Learn more: https://shoulder.dev/learn/go/cwe-502/llm-training-data-poisoning