CWE-174 对同一数据的双重编码

Double Decoding of the Same Data

结构: Simple

Abstraction: Variant

状态: Draft

被利用可能性: unkown

基本描述

The software decodes the same input twice, which can limit the effectiveness of any protection mechanism that occurs in between the decoding operations.

相关缺陷

• cwe_Nature: ChildOf cwe_CWE_ID: 172 cwe_View_ID: 1000

• cwe_Nature: ChildOf cwe_CWE_ID: 172 cwe_View_ID: 699 cwe_Ordinal: Primary

• cwe_Nature: ChildOf cwe_CWE_ID: 675 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', 'Confidentiality', 'Availability', 'Integrity', 'Other']	['Bypass Protection Mechanism', 'Execute Unauthorized Code or Commands', 'Varies by Context']

可能的缓解方案

MIT-44 Architecture and Design

策略: Input Validation

Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.

MIT-5 Implementation

策略: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs (i.e., do not rely on a blacklist). A blacklist is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

MIT-30 Implementation

策略: Output Encoding

Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.

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.

分析过的案例

标识	说明	链接
CVE-2004-1315	Forum software improperly URL decodes the highlight parameter when extracting text to highlight, which allows remote attackers to execute arbitrary PHP code by double-encoding the highlight value so that special characters are inserted into the result.	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-1315
CVE-2004-1939	XSS protection mechanism attempts to remove "/" that could be used to close tags, but it can be bypassed using double encoded slashes (%252F)	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-1939
CVE-2001-0333	Directory traversal using double encoding.	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2001-0333
CVE-2004-1938	"%2527" (double-encoded single quote) used in SQL injection.	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-1938
CVE-2005-1945	Double hex-encoded data.	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-1945
CVE-2005-0054	Browser executes HTML at higher privileges via URL with hostnames that are double hex encoded, which are decoded twice to generate a malicious hostname.	https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-0054

Notes

分类映射

映射的分类名	ImNode ID	Fit	Mapped Node Name
PLOVER			Double Encoding