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Description
The software receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as macro symbols when they are sent to a downstream component.
Modes of Introduction:
– Implementation
Related Weaknesses
CWE-138
Consequences
Integrity: Unexpected State
Potential Mitigations
Phase: Implementation
Description:
Developers should anticipate that macro symbols will be injected/removed/manipulated in the input vectors of their software system. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
Phase: Implementation
Description:
Phase: Implementation
Description:
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.
Phase: Implementation
Description:
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 allowlist validation schemes by introducing dangerous inputs after they have been checked.
CVE References
- CVE-2002-0770
- Server trusts client to expand macros, allows macro characters to be expanded to trigger resultant information exposure.
- CVE-2008-2018
- Attacker can obtain sensitive information from a database by using a comment containing a macro, which inserts the data during expansion.
