CWE-180 不正确的行为次序：规范化之前验证
Incorrect Behavior Order: Validate Before Canonicalize
结构: Simple
Abstraction: Base
状态: Draft
被利用可能性: unkown
基本描述
The software validates input before it is canonicalized, which prevents the software from detecting data that becomes invalid after the canonicalization step.
扩展描述
This can be used by an attacker to bypass the validation and launch attacks that expose weaknesses that would otherwise be prevented, such as injection.
相关缺陷
-
cwe_Nature: ChildOf cwe_CWE_ID: 20 cwe_View_ID: 699 cwe_Ordinal: Primary
-
cwe_Nature: ChildOf cwe_CWE_ID: 179 cwe_View_ID: 1000 cwe_Ordinal: Primary
适用平台
Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}
常见的影响
| 范围 | 影响 | 注释 |
|---|---|---|
| Access Control | Bypass Protection Mechanism |
可能的缓解方案
MIT-20 Implementation
策略: Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass whitelist validation schemes by introducing dangerous inputs after they have been checked.
示例代码
例
The following code attempts to validate a given input path by checking it against a whitelist and then return the canonical path. In this specific case, the path is considered valid if it starts with the string "/safe_dir/".
bad Java
if (path.startsWith("/safe_dir/"))
{
return f.getCanonicalPath();
}
The problem with the above code is that the validation step occurs before canonicalization occurs. An attacker could provide an input path of "/safe_dir/../" that would pass the validation step. However, the canonicalization process sees the double dot as a traversal to the parent directory and hence when canonicized the path would become just "/".
To avoid this problem, validation should occur after canonicalization takes place. In this case canonicalization occurs during the initialization of the File object. The code below fixes the issue.
good Java
File f = new File(path);
if (f.getCanonicalPath().startsWith("/safe_dir/"))
{
}
分析过的案例
| 标识 | 说明 | 链接 |
|---|---|---|
| CVE-2002-0433 | Product allows remote attackers to view restricted files via an HTTP request containing a "*" (wildcard or asterisk) character. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2002-0433 |
| CVE-2003-0332 | Product modifies the first two letters of a filename extension after performing a security check, which allows remote attackers to bypass authentication via a filename with a .ats extension instead of a .hts extension. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2003-0332 |
| CVE-2002-0802 | Database consumes an extra character when processing a character that cannot be converted, which could remove an escape character from the query and make the application subject to SQL injection attacks. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2002-0802 |
| CVE-2000-0191 | Overlaps "fakechild/../realchild" | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-0191 |
| CVE-2004-2363 | Product checks URI for " | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-2363 |
Notes
分类映射
| 映射的分类名 | ImNode ID | Fit | Mapped Node Name |
|---|---|---|---|
| PLOVER | Validate-Before-Canonicalize | ||
| OWASP Top Ten 2004 | A1 | CWE More Specific | Unvalidated Input |
| The CERT Oracle Secure Coding Standard for Java (2011) | IDS01-J | Exact | Normalize strings before validating them |
| SEI CERT Oracle Coding Standard for Java | IDS01-J | Exact | Normalize strings before validating them |
相关攻击模式
- CAPEC-267
- CAPEC-3
- CAPEC-71
- CAPEC-78
- CAPEC-79
- CAPEC-80
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