Описание
Issue summary: When an application drives an AES-OCB context through the
public EVP_Cipher() one-shot interface, the application-supplied
initialisation vector (IV) is silently discarded.
Impact summary: Every message encrypted under the same key uses the
same effective nonce regardless of the IV supplied by the caller,
resulting in (key, nonce) reuse and loss of confidentiality. If the
same code path is used to compute the authentication tag, the tag
depends only on the (key, IV) pair and not on the plaintext or
ciphertext, allowing universal forgery of arbitrary ciphertext from a
single captured message.
OpenSSL provides two ways to drive a cipher: the documented streaming
interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level
one-shot, EVP_Cipher(), whose documentation explicitly recommends
against use by applications in favour of EVP_CipherUpdate() and
EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes
the application-supplied IV into the OCB context before processing
data; the one-shot handler did not. Every call to EVP_Cipher() on an
AES-OCB context therefore ran with the all-zero key-derived offset
state left by cipher initialisation, regardless of the caller's IV.
If EVP_EncryptFinal_ex() is subsequently used to obtain the
authentication tag, the deferred IV setup runs at that point and
clears the running checksum that should have been accumulated over the
plaintext. The resulting tag is a function of (key, IV) only and
verifies against any ciphertext produced under the same (key, IV)
pair.
The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a
TLS cipher suite, and libssl does not call EVP_Cipher() in any case.
Applications that drive AES-OCB through the documented streaming AEAD
API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only
applications that combine the AES-OCB cipher with the EVP_Cipher()
one-shot API are vulnerable.
The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by
this issue, as AES-OCB is outside the OpenSSL FIPS module boundary.
A flaw was found in OpenSSL. Applications that use the AES-OCB encryption method with a specific one-shot interface (EVP_Cipher()) will have their provided Initialization Vector (IV) silently discarded. This leads to the same internal cryptographic value being used repeatedly, which compromises the confidentiality of encrypted data. Additionally, this issue allows for the universal forgery of authentication tags, undermining the integrity of communications.
Отчет
This is a Moderate severity flaw where applications utilizing the AES-OCB cipher through OpenSSL's EVP_Cipher() one-shot interface may silently discard the provided initialization vector (IV). This leads to nonce reuse, compromising confidentiality and enabling universal forgery of authentication tags. Red Hat products are primarily affected if they include or rely on third-party applications that specifically employ this less common and discouraged API usage with AES-OCB, as standard OpenSSL SSL/TLS implementations and applications using the recommended streaming AEAD API are not impacted.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | edk2 | Not affected | ||
| Red Hat Enterprise Linux 10 | shim | Not affected | ||
| Red Hat Enterprise Linux 10 | shim-unsigned-aarch64 | Not affected | ||
| Red Hat Enterprise Linux 10 | shim-unsigned-x64 | Not affected | ||
| Red Hat Enterprise Linux 6 | openssl | Not affected | ||
| Red Hat Enterprise Linux 7 | ovmf | Not affected | ||
| Red Hat Enterprise Linux 8 | compat-openssl10 | Not affected | ||
| Red Hat Enterprise Linux 8 | edk2 | Not affected | ||
| Red Hat Enterprise Linux 8 | mingw-openssl | Not affected | ||
| Red Hat Enterprise Linux 8 | openssl | Not affected |
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Дополнительная информация
Статус:
EPSS
9.1 Critical
CVSS3
Связанные уязвимости
Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot interface, the application-supplied initialisation vector (IV) is silently discarded. Impact summary: Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message. OpenSSL provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes the application-supplied IV into the OCB conte...
Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot interface, the application-supplied initialisation vector (IV) is silently discarded. Impact summary: Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message. OpenSSL provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes the application-supplied IV into the OCB contex
Issue summary: When an application drives an AES-OCB context through t ...
Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot interface, the application-supplied initialisation vector (IV) is silently discarded. Impact summary: Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message. OpenSSL provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes the application-supplied IV into the OCB con...
EPSS
9.1 Critical
CVSS3