SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-3712

If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit.

HIGH 7.4EPSS 50.4%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 50.4%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.

Description

ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's own "d2i" functions (and other similar parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array by directly setting the "data" and "length" fields in the ASN1_STRING array. This can also happen by using the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for strings that have been directly constructed. Where an application requests an ASN.1 structure to be printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the application without NUL terminating the "data" field, then a read buffer overrun can occur. The same thing can also occur during name constraints processing of certificates (for example if a certificate has been directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack). It could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).

CVSS 3.1
7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS
50.44% probability · 99th percentile
CISA KEV
Not listed
Weakness
CWE-125
Affected
openssl/openssl · debian/debian linux · netapp/clustered data ontap · netapp/clustered data ontap antivirus connector · netapp/e-series santricity os controller · netapp/hci management node · netapp/manageability software development kit · netapp/santricity smi-s provider · netapp/solidfire · netapp/storage encryption · mcafee/epolicy orchestrator · tenable/nessus network monitor · tenable/tenable.sc · oracle/essbase · oracle/mysql connectors · oracle/mysql enterprise monitor · oracle/mysql server · oracle/mysql workbench · oracle/peoplesoft enterprise peopletools · oracle/secure backup · +12 more
Source
openssl-security@openssl.org

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.