CVE-2024-9143

Issue summary: Use of the low-level GF(2^m) elliptic curve APIs with untrusted explicit values for the field polynomial can lead to out-of-bounds memory reads or writes.

Impact summary: Out of bound memory writes can lead to an application crash or even a possibility of a remote code execution, however, in all the protocols involving Elliptic Curve Cryptography that were aware of, either only named curves are supported, or, if explicit curve parameters are supported, they specify an X9.62 encoding of binary (GF(2^m)) curves that cant represent problematic input values. Thus the likelihood of existence of a vulnerable application is low.

In particular, the X9.62 encoding is used for ECC keys in X.509 certificates, so problematic inputs cannot occur in the context of processing X.509 certificates. Any problematic use-cases would have to be using an exotic curve encoding.

The affected APIs include: EC_GROUP_new_curve_GF2m(), EC_GROUP_new_from_params(), and various supporting BN_GF2m_*() functions.

Applications working with exotic explicit binary (GF(2^m)) curve parameters, that make it possible to represent invalid field polynomials with a zero constant term, via the above or similar APIs, may terminate abruptly as a result of reading or writing outside of array bounds. Remote code execution cannot easily be ruled out.

The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• 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.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://github.com/openssl/openssl/commit/72ae83ad214d2eef262461365a1975707f862712
• https://github.com/openssl/openssl/commit/bc7e04d7c8d509fb78fc0e285aa948fb0da04700
• https://github.com/openssl/openssl/commit/c0d3e4d32d2805f49bec30547f225bc4d092e1f4
• https://github.com/openssl/openssl/commit/fdf6723362ca51bd883295efe206cb5b1cfa5154
• https://github.openssl.org/openssl/extended-releases/commit/8efc0cbaa8ebba8e116f7b81a876a4123594d86a
• https://github.openssl.org/openssl/extended-releases/commit/9d576994cec2b7aa37a91740ea7e680810957e41
• https://openssl-library.org/news/secadv/20241016.txt
• http://www.openwall.com/lists/oss-security/2024/10/16/1
• http://www.openwall.com/lists/oss-security/2024/10/23/1
• http://www.openwall.com/lists/oss-security/2024/10/24/1
• https://security.netapp.com/advisory/ntap-20241101-0001/