Date: Tue, 30 May 2023 13:49:33 +0000 From: Tomas Mraz <tomas@...nssl.org> To: oss-security@...ts.openwall.com Subject: OpenSSL Security Advisory -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 OpenSSL Security Advisory [30th May 2023] ========================================= Possible DoS translating ASN.1 object identifiers (CVE-2023-2650) ================================================================= Severity: Moderate Issue summary: Processing some specially crafted ASN.1 object identifiers or data containing them may be very slow. Impact summary: Applications that use OBJ_obj2txt() directly, or use any of the OpenSSL subsystems OCSP, PKCS7/SMIME, CMS, CMP/CRMF or TS with no message size limit may experience notable to very long delays when processing those messages, which may lead to a Denial of Service. An OBJECT IDENTIFIER is composed of a series of numbers - sub-identifiers - most of which have no size limit. OBJ_obj2txt() may be used to translate an ASN.1 OBJECT IDENTIFIER given in DER encoding form (using the OpenSSL type ASN1_OBJECT) to its canonical numeric text form, which are the sub-identifiers of the OBJECT IDENTIFIER in decimal form, separated by periods. When one of the sub-identifiers in the OBJECT IDENTIFIER is very large (these are sizes that are seen as absurdly large, taking up tens or hundreds of KiBs), the translation to a decimal number in text may take a very long time. The time complexity is O(n^2) with 'n' being the size of the sub-identifiers in bytes (*). With OpenSSL 3.0, support to fetch cryptographic algorithms using names / identifiers in string form was introduced. This includes using OBJECT IDENTIFIERs in canonical numeric text form as identifiers for fetching algorithms. Such OBJECT IDENTIFIERs may be received through the ASN.1 structure AlgorithmIdentifier, which is commonly used in multiple protocols to specify what cryptographic algorithm should be used to sign or verify, encrypt or decrypt, or digest passed data. Applications that call OBJ_obj2txt() directly with untrusted data are affected, with any version of OpenSSL. If the use is for the mere purpose of display, the severity is considered low. In OpenSSL 3.0 and newer, this affects the subsystems OCSP, PKCS7/SMIME, CMS, CMP/CRMF or TS. It also impacts anything that processes X.509 certificates, including simple things like verifying its signature. The impact on TLS is relatively low, because all versions of OpenSSL have a 100KiB limit on the peer's certificate chain. Additionally, this only impacts clients, or servers that have explicitly enabled client authentication. In OpenSSL 1.1.1 and 1.0.2, this only affects displaying diverse objects, such as X.509 certificates. This is assumed to not happen in such a way that it would cause a Denial of Service, so these versions are considered not affected by this issue in such a way that it would be cause for concern, and the severity is therefore considered low. No version of the FIPS provider is affected by this issue. OpenSSL 3.0.x and 3.1.x are vulnerable to this issue. OpenSSL 1.1.1 and 1.0.2 users may be affected by this issue when calling OBJ_obj2txt() directly. OpenSSL 3.0 users should upgrade to OpenSSL 3.0.9. OpenSSL 3.1 users should upgrade to OpenSSL 3.1.1. OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1u. OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zh (premium support customers only). OSSfuzz first detected and automatically reported this issue on 16th January 2020. At that time OpenSSL 3.0 was still in early development and it was not identified as a security concern at that time. On 23rd April 2023 the issue was reexamined and identified as a security issue by Matt Caswell. The fix was developed by Richard Levitte. (*) A measurement showed about 2 seconds for 100KiB and a minute for 500KiB. This measurement wasn't made to demonstrate exact time ranges, but rather to demonstrate the quadratic nature of the issue. General Advisory Notes ====================== URL for this Security Advisory: https://www.openssl.org/news/secadv/20230530.txt Note: the online version of the advisory may be updated with additional details over time. For details of OpenSSL severity classifications please see: https://www.openssl.org/policies/general/security-policy.html OpenSSL 1.1.1 will reach end-of-life on 2023-09-11. After that date security fixes for 1.1.1 will only be available to premium support customers. -----BEGIN PGP SIGNATURE----- iQJGBAEBCAAwFiEE3HAyZir4heL0fyQ/UnRmohynnm0FAmR1/kQSHHRvbWFzQG9w ZW5zc2wub3JnAAoJEFJ0ZqIcp55tXS0QAJpUoGfoirteiNuvdRy4PP72E0ZHVsll 2PlsArtQwogpEJD5Z4Escq+Cb7ZPl7uqBdfosJTX31Kr3e/ri6HY3Bzjxa1xOKUo GHC/RADZqGWemBiabr9BDtJAaadQDS3a8tGSklgab0ueHtCX9zX0ptWE3lW8NGp5 DXQ4pBVzGHpldHgN8OLhpreshbw9RJNvdAXrl445MtUNXy4rJYRTqlHCqwH6qjCM a/a6sFaIevgspm85L30YWtx38T+vqfNFhl9RZuKbQB9PlL1g3UWpsnvVUCSrXytH ehlNhyfCX03vNn4Ym/Gp9cj5/1EM0wsF6EVuXGBe6+D/vwh5eLTPgndLr8KKo12C ysJF4dGdLSKg3KaL6xV4Km+XXv8S4s4MF9FOYqachF6hnBWyTdwkVcTNWBYPmexS Kw/MpXku65hWrjZT9FGfoFsl3RBYOde9E31ubd6/gUANkzF8jqaMfn966oCmoz2O uQb29gjEKUQWZD8Es23Yub3Jj0wTvN1i03fIhrzzbgoIR/RGOX/4yTKvsoYk2ddG +30PPLKXrckQ+n4GT8eq1Fdr6ReKjuMpH3b85Ki2pSuwRY666P+pqWwuV9BGT1QP uKiSvF4nxdLs4VExQ9XN42zPC6rKKu5t9XxC5xdYEGUKlTxFshDL4dHn93tpl0T3 vuVUvn6INUsN =xLMN -----END PGP SIGNATURE-----
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