CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.
扩展描述
If the DTD contains a large number of nested or recursive entities, this can lead to explosive growth of data when parsed, causing a denial of service.
常见后果
影响范围: Availability
技术影响: DoS: Resource Consumption (Other)
说明: If parsed, recursive entity references allow the attacker to expand data exponentially, quickly consuming all system resources.
潜在缓解措施
阶段: Operation
描述: If possible, prohibit the use of DTDs or use an XML parser that limits the expansion of recursive DTD entities.
阶段: Implementation
描述: Before parsing XML files with associated DTDs, scan for recursive entity declarations and do not continue parsing potentially explosive content.
检测方法
方法: Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
有效性: High
观察示例
参考: CVE-2008-3281
XEE in XML-parsing library.
参考: CVE-2011-3288
XML bomb / XEE in enterprise communication product.
参考: CVE-2011-1755
"Billion laughs" attack in XMPP server daemon.
参考: CVE-2009-1955
XML bomb in web server module
参考: CVE-2003-1564
Parsing library allows XML bomb
引入模式
| 阶段 | 说明 |
|---|---|
| Implementation | - |
| Operation | - |
适用平台
编程语言
分类映射
| 分类名称 | 条目ID | 条目名称 | 映射适配度 |
|---|---|---|---|
| WASC | 44 | XML Entity Expansion | - |