Improper Control of Document Type Definition

Opis

The product does not restrict a reference to a Document Type Definition (DTD) to the intended control sphere. This might allow attackers to reference arbitrary DTDs, possibly causing the product to expose files, consume excessive system resources, or execute arbitrary http requests on behalf of the attacker.

As DTDs are processed, they might try to read or include files on the machine performing the parsing. If an attacker is able to control the DTD, then the attacker might be able to specify sensitive resources or requests or provide malicious content.

For example, the SOAP specification prohibits SOAP messages from containing DTDs.

Skutki

• Confidentiality

  Read Files or Directories

  If the attacker is able to include a crafted DTD and a default entity resolver is enabled, the attacker may be able to access arbitrary files on the system.

• Availability

  DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)

  The DTD may cause the parser to consume excessive CPU cycles or memory using techniques such as nested or recursive entity references (CWE-776).

• Integrity, Confidentiality, Availability, Access Control

  Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity

  The DTD may include arbitrary HTTP requests that the server may execute. This could lead to other attacks leveraging the server's trust relationship with other entities.

Przykłady podatności

• CVE-2010-2076 Product does not properly reject DTDs in SOAP messages, which allows remote attackers to read arbitrary files, send HTTP requests to intranet servers, or cause a denial of service.

Słabość nadrzędna

• CWE-706 Use of Incorrectly-Resolved Name or Reference
• CWE-829 Inclusion of Functionality from Untrusted Control Sphere

Może prowadzić do

• CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

Kiedy powstaje

• Implementation — REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Dotyczy

XML

Źródła

1. Apache CXF Security Advisory (CVE-2010-2076) — Daniel Kulp, 2010