Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection')

Opis

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before inserting the input into an executable resource, such as a library, configuration file, or template.

Skutki

• Confidentiality

  Read Files or Directories; Read Application Data

  The injected code could access restricted data / files.

• Access Control

  Bypass Protection Mechanism

  In some cases, injectable code controls authentication; this may lead to a remote vulnerability.

• Access Control

  Gain Privileges or Assume Identity

  Injected code can access resources that the attacker is directly prevented from accessing.

• Integrity, Confidentiality, Availability, Other

  Execute Unauthorized Code or Commands

  Code injection attacks can lead to loss of data integrity in nearly all cases as the control-plane data injected is always incidental to data recall or writing. Additionally, code injection can often result in the execution of arbitrary code.

• Non-Repudiation

  Hide Activities

  Often the actions performed by injected control code are unlogged.

Zapobieganie

• Implementation · Input Validation

  Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list 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. This 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, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

• Implementation · Output Encoding

  Perform proper output validation and escaping to neutralize all code syntax from data written to code files.

Przykłady podatności

• CVE-2002-0495 Perl code directly injected into CGI library file from parameters to another CGI program.
• CVE-2005-1876 Direct PHP code injection into supporting template file.
• CVE-2005-1894 Direct code injection into PHP script that can be accessed by attacker.
• CVE-2003-0395 PHP code from User-Agent HTTP header directly inserted into log file implemented as PHP script.
• CVE-2007-6652 chain: execution after redirect allows non-administrator to perform static code injection.

Słabość nadrzędna

• CWE-94 Improper Control of Generation of Code ('Code Injection')

Słabości podrzędne

• CWE-97 Improper Neutralization of Server-Side Includes (SSI) Within a Web Page

Kiedy powstaje

• Implementation — REALIZATION: This weakness is caused during implementation of an architectural security tactic.
• Implementation — This issue is frequently found in PHP applications that allow users to set configuration variables that are stored within executable PHP files. Technically, this could also be performed in some compiled code (e.g., by byte-patching an executable), although it is highly unlikely.

Dotyczy

PHP, Perl, Interpreted

Uwagi

"HTML injection" (see CWE-79: XSS) could be thought of as an example of this, but the code is injected and executed on the client side, not the server side. Server-Side Includes (SSI) are an example of direct static code injection.