Multiple vulnerabilities in Tenable Nessus Agent

Published: 2021-03-19 | Updated: 2022-06-03

Risk	Medium
Patch available	YES
Number of vulnerabilities	3
CVE-ID	CVE-2021-23840 CVE-2021-23841 CVE-2021-20077
CWE-ID	CWE-20 CWE-476 CWE-200
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	Nessus Agent Client/Desktop applications / Other client software
Vendor	Tenable Network Security

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) Input validation error

EUVDB-ID: #VU50745

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23840

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Nessus Agent: 7.2.0 - 8.2.2

CPE2.3

External links

http://www.tenable.com/security/tns-2021-04-0

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) NULL pointer dereference

EUVDB-ID: #VU50740

Risk: Medium

CVSSv3.1: 5.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23841

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Nessus Agent: 7.2.0 - 8.2.2

CPE2.3

External links

http://www.tenable.com/security/tns-2021-04-0

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Information disclosure

EUVDB-ID: #VU51578

Risk: Low

CVSSv3.1: 2 [CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-20077

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a local user to gain access to potentially sensitive information.

The vulnerability exists due to Nessus Agent inadvertently captures the IAM role security token on the local host during initial linking of the Nessus Agent when installed on an Amazon EC2 instance. A local privileged user can obtain the token.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Nessus Agent: 7.2.0 - 8.2.2

CPE2.3

External links

http://www.tenable.com/security/tns-2021-04-0

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.