CWE WEAKNESSES / CWE-203
CWE-203
Observable Discrepancy
Base
What it is
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
Impact
| Confidentiality, Access Control | Read Application Data, Bypass Protection Mechanism |
| Confidentiality | Read Application Data |
Mitigations
- [Architecture and Design]Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separ
- [Implementation]Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine
Real-world CVE examples
- CVE-2020-8695 — Observable discrepancy in the RAPL interface for some Intel processors allows information disclosure.
- CVE-2019-14353 — Crypto hardware wallet's power consumption relates to total number of pixels illuminated, creating a side channel in the USB connection that allows attackers to
- CVE-2019-10071 — Java-oriented framework compares HMAC signatures using String.equals() instead of a constant-time algorithm, causing timing discrepancies
- CVE-2002-2094 — This, and others, use ".." attacks and monitor error responses, so there is overlap with directory traversal.
- CVE-2001-1483 — Enumeration of valid usernames based on inconsistent responses
- CVE-2001-1528 — Account number enumeration via inconsistent responses.
- CVE-2004-2150 — User enumeration via discrepancies in error messages.
- CVE-2005-1650 — User enumeration via discrepancies in error messages.
- CVE-2004-0294 — Bulletin Board displays different error messages when a user exists or not, which makes it easier for remote attackers to identify valid users and conduct a bru
- CVE-2004-0243 — Operating System, when direct remote login is disabled, displays a different message if the password is correct, which allows remote attackers to guess the pass
- CVE-2002-0514 — Product allows remote attackers to determine if a port is being filtered because the response packet TTL is different than the default TTL.
- CVE-2002-0515 — Product sets a different TTL when a port is being filtered than when it is not being filtered, which allows remote attackers to identify filtered ports by compa
Related weaknesses
Test & detect
Browse all common weaknesses, check related exploited CVEs, or map to ATT&CK techniques.
Source: MITRE CWE. View on cwe.mitre.org →