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Mbed TLS 2.16.7
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@yanesca yanesca released this 01 Jul 14:03
v2.16.7
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Description

Mbed TLS 2.16.7 is a maintenance release of the Mbed TLS 2.16 branch, and provides bug fixes and minor enhancements. This release includes fixes for security issues and the most severe one is described in more detail in a security advisory.

Security

  • Fix a side channel vulnerability in modular exponentiation that could reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee, Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul Strackx (Fortanix) in #3394.
  • Fix side channel in mbedtls_ecp_check_pub_priv() and mbedtls_pk_parse_key() / mbedtls_pk_parse_keyfile() (when loading a private key that didn't include the uncompressed public key), as well as mbedtls_ecp_mul() / mbedtls_ecp_mul_restartable() when called with a NULL f_rng argument. An attacker with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave) could fully recover the ECC private key. Found and reported by Alejandro Cabrera Aldaya and Billy Brumley.
  • Fix issue in Lucky 13 counter-measure that could make it ineffective when hardware accelerators were used (using one of the MBEDTLS_SHAxxx_ALT macros). This would cause the original Lucky 13 attack to be possible in those configurations, allowing an active network attacker to recover plaintext after repeated timing measurements under some conditions. Reported and fix suggested by Luc Perneel in #3246.

Bugfix

  • Fix the Visual Studio Release x64 build configuration for mbedtls itself. Completes a previous fix in Mbed TLS 2.16.3 that only fixed the build for the example programs. Reported in #1430 and fix contributed by irwir.
  • Fix undefined behavior in X.509 certificate parsing if the pathLenConstraint basic constraint value is equal to INT_MAX. The actual effect with almost every compiler is the intended behavior, so this is unlikely to be exploitable anywhere. #3197
  • Include asn1.h in error.c. Fixes #3328 reported by David Hu.
  • Fix potential memory leaks in ecp_randomize_jac() and ecp_randomize_mxz() when PRNG function fails. Contributed by Jonas Lejeune in #3318.
  • Add additional bounds checks in ssl_write_client_hello() preventing output buffer overflow if the configuration declared a buffer that was too small.

Changes

  • Unify the example programs termination to call mbedtls_exit() instead of using a return command. This has been done to enable customization of the behavior in bare metal environments.
  • Abort the ClientHello writing function as soon as some extension doesn't fit into the record buffer. Previously, such extensions were silently dropped. As a consequence, the TLS handshake now fails when the output buffer is not large enough to hold the ClientHello.
  • The ECP module, enabled by MBEDTLS_ECP_C, now depends on MBEDTLS_CTR_DRBG_C, MBEDTLS_HMAC_DRBG_C, MBEDTLS_SHA512_C or MBEDTLS_SHA256_C for some side-channel coutermeasures. If side channels are not a concern, this dependency can be avoided by enabling the new option MBEDTLS_ECP_NO_INTERNAL_RNG.

Who should update

We recommend all affected users should update to take advantage of the bug fixes contained in this release at an appropriate point in their development lifecycle.

Checksum

The SHA256 hashes for the archives are:

c95b11557ee97d2bdfd48cd57cf9b648a6cddd2ca879e3c35c4e7525f2871992  mbedtls-2.16.7.tar.gz
6ee853f8dbbe662b7647b454c9635ed7f2b3c78293e064c1be74c7cfd97d080b  mbedtls-2.16.7.zip
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