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.

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.

This update for mbedtls fixes the following issues :

  - mbedtls was updated to version 2.16.9

  - CVE-2020-10932: Fixed side channel in ECC code that     allowed an adversary with access to precise enough     timing and memory access information (typically an     untrusted operating system attacking a secure enclave)     to fully recover an ECDSA private key (boo#1181468).

- Update to 2.16.6

Release notes:
https://tls.mbed.org/tech-updates/releases/mbedtls-2.16.6-and-2.7.15-r eleased

Security Advisory:
https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security
-advisory-2020-04

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 :

An attacker with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) can fully recover an ECDSA private key after observing a number of signature operations.

ID	Name	Product	Family	Severity
169300	Debian DLA-3249-1 : mbedtls - LTS security update	Nessus	Debian Local Security Checks	critical
147174	openSUSE Security Update : mbedtls (openSUSE-2021-384)	Nessus	SuSE Local Security Checks	medium
137162	Fedora 32 : mbedtls (2020-9a6e8e63e9)	Nessus	Fedora Local Security Checks	medium
137158	Fedora 31 : mbedtls (2020-42564738a1)	Nessus	Fedora Local Security Checks	medium
135604	FreeBSD : Mbed TLS -- Side channel attack on ECDSA (bf1f47c4-7f1b-11ea-bf94-001cc0382b2f)	Nessus	FreeBSD Local Security Checks	medium

Detections

Analytics

CVE-2020-10932

medium

Tenable Plugins

critical

medium

medium

medium

medium