Vulnerability CVE-2021-3712


Published: 2021-08-24

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).

Type:

CWE-125

(Out-of-bounds Read)

CVSS2 => (AV:N/AC:M/Au:N/C:P/I:N/A:P)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5.8/10
4.9/10
8.6/10
Exploit range
Attack complexity
Authentication
Remote
Medium
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
None
Partial
Affected software
Openssl -> Openssl 
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 
Debian -> Debian linux 

 References:
https://www.openssl.org/news/secadv/20210824.txt
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=94d23fcff9b2a7a8368dfe52214d5c2569882c11
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=ccb0a11145ee72b042d10593a64eaf9e8a55ec12
https://www.debian.org/security/2021/dsa-4963
https://lists.apache.org/thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e@%3Cdev.tomcat.apache.org%3E
http://www.openwall.com/lists/oss-security/2021/08/26/2
https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1@%3Cdev.tomcat.apache.org%3E
https://security.netapp.com/advisory/ntap-20210827-0010/

Copyright 2022, cxsecurity.com

 

Back to Top