OESA-2023-1092

OpenSSL is a robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols.

Security Fix(es):

The public API function BIOnewNDEF is a helper function used for streaming ASN.1 data via a BIO. It is primarily used internally to OpenSSL to support the SMIME, CMS and PKCS7 streaming capabilities, but may also be called directly by end user applications. The function receives a BIO from the caller, prepends a new BIOfasn1 filter BIO onto the front of it to form a BIO chain, and then returns the new head of the BIO chain to the caller. Under certain conditions, for example if a CMS recipient public key is invalid, the new filter BIO is freed and the function returns a NULL result indicating a failure. However, in this case, the BIO chain is not properly cleaned up and the BIO passed by the caller still retains internal pointers to the previously freed filter BIO. If the caller then goes on to call BIOpop() on the BIO then a use-after-free will occur. This will most likely result in a crash. This scenario occurs directly in the internal function B64writeASN1() which may cause BIOnewNDEF() to be called and will subsequently call BIOpop() on the BIO. This internal function is in turn called by the public API functions PEMwritebioASN1stream, PEMwritebioCMSstream, PEMwritebioPKCS7stream, SMIMEwriteASN1, SMIMEwriteCMS and SMIMEwritePKCS7. Other public API functions that may be impacted by this include i2dASN1biostream, BIOnewCMS, BIOnewPKCS7, i2dCMSbiostream and i2dPKCS7bio_stream. The OpenSSL cms and smime command line applications are similarly affected.(CVE-2023-0215)

A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.(CVE-2022-4304)

The function PEMreadbioex() reads a PEM file from a BIO and parses and decodes the "name" (e.g. "CERTIFICATE"), any header data and the payload data. If the function succeeds then the "nameout", "header" and "data" arguments are populated with pointers to buffers containing the relevant decoded data. The caller is responsible for freeing those buffers. It is possible to construct a PEM file that results in 0 bytes of payload data. In this case PEMreadbioex() will return a failure code but will populate the header argument with a pointer to a buffer that has already been freed. If the caller also frees this buffer then a double free will occur. This will most likely lead to a crash. This could be exploited by an attacker who has the ability to supply malicious PEM files for parsing to achieve a denial of service attack. The functions PEMreadbio() and PEMread() are simple wrappers around PEMreadbioex() and therefore these functions are also directly affected. These functions are also called indirectly by a number of other OpenSSL functions including PEMX509INFOreadbioex() and SSLCTXuseserverinfofile() which are also vulnerable. Some OpenSSL internal uses of these functions are not vulnerable because the caller does not free the header argument if PEMreadbioex() returns a failure code. These locations include the PEMreadbioTYPE() functions as well as the decoders introduced in OpenSSL 3.0. The OpenSSL asn1parse command line application is also impacted by this issue.(CVE-2022-4450)

There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName. X.400 addresses were parsed as an ASN1STRING but the public structure definition for GENERALNAME incorrectly specified the type of the x400Address field as ASN1TYPE. This field is subsequently interpreted by the OpenSSL function GENERALNAMEcmp as an ASN1TYPE rather than an ASN1STRING. When CRL checking is enabled (i.e. the application sets the X509VFLAGCRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network.(CVE-2023-0286)