SB2021051226 - Multiple vulnerabilities in Nessus Network Monitor

Description

This security bulletin contains information about 5 secuirty vulnerabilities.

1) NULL pointer dereference (CVE-ID: CVE-2020-1971)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error. A remote attacker can trigger denial of service conditions via the API functions TS_RESP_verify_response and TS_RESP_verify_token). If an attacker can control both items being compared then that attacker could trigger a crash. For example if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then this may occur. Note that some applications automatically download CRLs based on a URL embedded in a certificate. This checking happens prior to the signatures on the certificate and CRL being verified. OpenSSL's s_server, s_client and verify tools have support for the "-crl_download" option which implements automatic CRL downloading and this attack has been demonstrated to work against those tools. Note that an unrelated bug means that affected versions of OpenSSL cannot parse or construct correct encodings of EDIPARTYNAME. However it is possible to construct a malformed EDIPARTYNAME that OpenSSL's parser will accept and hence trigger this attack.

2) Input validation error (CVE-ID: CVE-2021-23840)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input during EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate calls. A remote attacker can pass specially crafted input to the application and perform a denial of service (DoS) attack.

3) NULL pointer dereference (CVE-ID: CVE-2021-23841)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error within the X509_issuer_and_serial_hash() function when parsing the issuer field in the X509 certificate. A remote attacker can supply a specially crafted certificate, trigger a NULL pointer dereference error and perform a denial of service (DoS) attack.

4) NULL pointer dereference (CVE-ID: CVE-2021-3449)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error when processing TLSv1.2 renegotiations. A remote attacker can send a maliciously crafted renegotiation ClientHello message, which omits the signature_algorithms extension but includes a signature_algorithms_cert extension, trigger a NULL pointer dereference error and crash the server.

5) Security features bypass (CVE-ID: CVE-2021-3450)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to an error in implementation of the X509_V_FLAG_X509_STRICT flag allows an attacker to overwrite a valid CA certificate using any non-CA certificate in the chain. As a result, a remote attacker can perform MitM attack.

Remediation

Install update from vendor's website.

References

• https://www.tenable.com/security/tns-2021-09