A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed TLS through 2.23.0 allows an attacker to recover secret key information. This affects CBC mode because of a computed time difference based on a padding length.

The remote host is affected by the vulnerability described in GLSA-202301-08 (Mbed TLS: Multiple Vulnerabilities)

  - A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed     TLS through 2.23.0 allows an attacker to recover secret key information. This affects CBC mode because of     a computed time difference based on a padding length. (CVE-2020-16150)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular     exponentiation, an RSA private key used in a secure enclave could be disclosed. (CVE-2020-36421)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. A side channel allows recovery of an ECC private     key, related to mbedtls_ecp_check_pub_priv, mbedtls_pk_parse_key, mbedtls_pk_parse_keyfile,     mbedtls_ecp_mul, and mbedtls_ecp_mul_restartable. (CVE-2020-36422)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. A remote attacker can recover plaintext because a     certain Lucky 13 countermeasure doesn't properly consider the case of a hardware accelerator.
    (CVE-2020-36423)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. An attacker can recover a private key (for RSA or     static Diffie-Hellman) via a side-channel attack against generation of base blinding/unblinding values.
    (CVE-2020-36424)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. It incorrectly uses a revocationDate check when     deciding whether to honor certificate revocation via a CRL. In some situations, an attacker can exploit     this by changing the local clock. (CVE-2020-36425)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. mbedtls_x509_crl_parse_der has a buffer over-read     (of one byte). (CVE-2020-36426)

  - An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). The     calculations performed by mbedtls_mpi_exp_mod are not limited; thus, supplying overly large parameters     could lead to denial of service when generating Diffie-Hellman key pairs. (CVE-2020-36475)

  - An issue was discovered in Mbed TLS before 2.24.0 (and before 2.16.8 LTS and before 2.7.17 LTS). There is     missing zeroization of plaintext buffers in mbedtls_ssl_read to erase unused application data from memory.
    (CVE-2020-36476)

  - An issue was discovered in Mbed TLS before 2.24.0. The verification of X.509 certificates when matching     the expected common name (the cn argument of mbedtls_x509_crt_verify) with the actual certificate name is     mishandled: when the subjecAltName extension is present, the expected name is compared to any name in that     extension regardless of its type. This means that an attacker could impersonate a 4-byte or 16-byte domain     by getting a certificate for the corresponding IPv4 or IPv6 address (this would require the attacker to     control that IP address, though). (CVE-2020-36477)

  - An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL     algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is     considered valid. However, if the parameters do not match in any way, then the certificate should be     considered invalid. (CVE-2020-36478)

  - A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation     function when an input password's length is 0. (CVE-2021-43666)

  - Mbed TLS before 3.0.1 has a double free in certain out-of-memory conditions, as demonstrated by an     mbedtls_ssl_set_session() failure. (CVE-2021-44732)

  - In Mbed TLS before 2.28.0 and 3.x before 3.1.0, psa_cipher_generate_iv and psa_cipher_encrypt allow policy     bypass or oracle-based decryption when the output buffer is at memory locations accessible to an untrusted     application. (CVE-2021-45450)

  - An issue was discovered in Mbed TLS before 2.28.1 and 3.x before 3.2.0. In some configurations, an     unauthenticated attacker can send an invalid ClientHello message to a DTLS server that causes a heap-based     buffer over-read of up to 255 bytes. This can cause a server crash or possibly information disclosure     based on error responses. Affected configurations have MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE enabled and     MBEDTLS_SSL_IN_CONTENT_LEN less than a threshold that depends on the configuration: 258 bytes if using     mbedtls_ssl_cookie_check, and possibly up to 571 bytes with a custom cookie check function.
    (CVE-2022-35409)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-3249 advisory.

  - Arm Mbed TLS before 2.19.0 and Arm Mbed Crypto before 2.0.0, when deterministic ECDSA is enabled, use an     RNG with insufficient entropy for blinding, which might allow an attacker to recover a private key via     side-channel attacks if a victim signs the same message many times. (For Mbed TLS, the fix is also     available in versions 2.7.12 and 2.16.3.) (CVE-2019-16910)

  - The ECDSA signature implementation in ecdsa.c in Arm Mbed Crypto 2.1 and Mbed TLS through 2.19.1 does not     reduce the blinded scalar before computing the inverse, which allows a local attacker to recover the     private key via side-channel attacks. (CVE-2019-18222)

  - An issue was discovered in Arm Mbed TLS before 2.16.6 and 2.7.x before 2.7.15. An attacker that can get     precise enough side-channel measurements can recover the long-term ECDSA private key by (1) reconstructing     the projective coordinate of the result of scalar multiplication by exploiting side channels in the     conversion to affine coordinates; (2) using an attack described by Naccache, Smart, and Stern in 2003 to     recover a few bits of the ephemeral scalar from those projective coordinates via several measurements; and     (3) using a lattice attack to get from there to the long-term ECDSA private key used for the signatures.
    Typically an attacker would have sufficient access when attacking an SGX enclave and controlling the     untrusted OS. (CVE-2020-10932)

  - Arm Mbed TLS before 2.16.5 allows attackers to obtain sensitive information (an RSA private key) by     measuring cache usage during an import. (CVE-2020-10941)

  - A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed     TLS through 2.23.0 allows an attacker to recover secret key information. This affects CBC mode because of     a computed time difference based on a padding length. (CVE-2020-16150)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular     exponentiation, an RSA private key used in a secure enclave could be disclosed. (CVE-2020-36421)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. A side channel allows recovery of an ECC private     key, related to mbedtls_ecp_check_pub_priv, mbedtls_pk_parse_key, mbedtls_pk_parse_keyfile,     mbedtls_ecp_mul, and mbedtls_ecp_mul_restartable. (CVE-2020-36422)

  - An issue was discovered in Arm Mbed TLS before 2.23.0. A remote attacker can recover plaintext because a     certain Lucky 13 countermeasure doesn't properly consider the case of a hardware accelerator.
    (CVE-2020-36423)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. An attacker can recover a private key (for RSA or     static Diffie-Hellman) via a side-channel attack against generation of base blinding/unblinding values.
    (CVE-2020-36424)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. It incorrectly uses a revocationDate check when     deciding whether to honor certificate revocation via a CRL. In some situations, an attacker can exploit     this by changing the local clock. (CVE-2020-36425)

  - An issue was discovered in Arm Mbed TLS before 2.24.0. mbedtls_x509_crl_parse_der has a buffer over-read     (of one byte). (CVE-2020-36426)

  - An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). The     calculations performed by mbedtls_mpi_exp_mod are not limited; thus, supplying overly large parameters     could lead to denial of service when generating Diffie-Hellman key pairs. (CVE-2020-36475)

  - An issue was discovered in Mbed TLS before 2.24.0 (and before 2.16.8 LTS and before 2.7.17 LTS). There is     missing zeroization of plaintext buffers in mbedtls_ssl_read to erase unused application data from memory.
    (CVE-2020-36476)

  - An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL     algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is     considered valid. However, if the parameters do not match in any way, then the certificate should be     considered invalid. (CVE-2020-36478)

  - In Trusted Firmware Mbed TLS 2.24.0, a side-channel vulnerability in base64 PEM file decoding allows     system-level (administrator) attackers to obtain information about secret RSA keys via a controlled-     channel and side-channel attack on software running in isolated environments that can be single stepped,     especially Intel SGX. (CVE-2021-24119)

  - A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation     function when an input password's length is 0. (CVE-2021-43666)

  - Mbed TLS before 3.0.1 has a double free in certain out-of-memory conditions, as demonstrated by an     mbedtls_ssl_set_session() failure. (CVE-2021-44732)

  - An issue was discovered in Mbed TLS before 2.28.1 and 3.x before 3.2.0. In some configurations, an     unauthenticated attacker can send an invalid ClientHello message to a DTLS server that causes a heap-based     buffer over-read of up to 255 bytes. This can cause a server crash or possibly information disclosure     based on error responses. Affected configurations have MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE enabled and     MBEDTLS_SSL_IN_CONTENT_LEN less than a threshold that depends on the configuration: 258 bytes if using     mbedtls_ssl_cookie_check, and possibly up to 571 bytes with a custom cookie check function.
    (CVE-2022-35409)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

- Update to 2.16.8

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Manuel Pegourie-Gonnard reports :

When decrypting/authenticating (D)TLS record in a connection using a CBC ciphersuite without the Encrypt-then-Mac extension RFC 7366, Mbed TLS used dummy rounds of the compression function associated with the hash used for HMAC in order to hide the length of the padding to remote attackers, as recommended in the original Lucky Thirteen paper.

A local attacker who is able to observe the state of the cache could monitor the presence of mbedtls_md_process() in the cache in order to determine when the actual computation ends and when the dummy rounds start. This is a reliable target as it's always called at least once, in response to a previous attack. The attacker can then continue with one of many well-documented Lucky 13 variants.

ID	Name	Product	Family	Severity
169842	GLSA-202301-08 : Mbed TLS: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	critical
169300	Debian DLA-3249-1 : mbedtls - LTS security update	Nessus	Debian Local Security Checks	critical
140762	Fedora 32 : mbedtls (2020-8b0d59bac6)	Nessus	Fedora Local Security Checks	medium
140621	Fedora 31 : mbedtls (2020-48a1ae610c)	Nessus	Fedora Local Security Checks	medium
140312	FreeBSD : Mbed TLS -- Local side channel attack on classical CBC decryption in (D)TLS (4c69240f-f02c-11ea-838a-0011d823eebd)	Nessus	FreeBSD Local Security Checks	medium

Detections

Analytics

CVE-2020-16150

medium

Tenable Plugins

critical

critical

medium

medium

medium