A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance     (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an     unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data     from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An     attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate     with an external server. A successful exploit could allow the attacker to execute a command-and-control     attack on a compromised host and perform additional data exfiltration attacks. (CVE-2021-34749)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote Debian 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-5354 advisory.

    Multiple security vulnerabilities were discovered in snort, a flexible Network Intrusion Detection System,     which could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or     bypass filtering technology on an affected device and ex-filtrate data from a compromised host. For the     stable distribution (bullseye), these problems have been fixed in version 2.9.20-0+deb11u1. We recommend     that you upgrade your snort packages. For the detailed security status of snort please refer to its     security tracker page at: https://security-tracker.debian.org/tracker/snort

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-3317 advisory.

    -------------------------------------------------------------------------     Debian LTS Advisory DLA-3317-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                      Markus Koschany     February 11, 2023                             https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : snort     Version        : 2.9.20-0+deb10u1     CVE ID         : CVE-2020-3299 CVE-2020-3315 CVE-2021-1223 CVE-2021-1224                      CVE-2021-1236 CVE-2021-1494 CVE-2021-1495 CVE-2021-34749                      CVE-2021-40114     Debian Bug     : 1021276

    Multiple security vulnerabilities were discovered in snort, a flexible Network     Intrusion Detection System, which could allow an unauthenticated, remote     attacker to cause a denial of service (DoS) condition or bypass filtering     technology on an affected device and ex-filtrate data from a compromised host.

    For Debian 10 buster, these problems have been fixed in version     2.9.20-0+deb10u1.

    We recommend that you upgrade your snort packages.

    For the detailed security status of snort please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/snort

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS     Attachment:
    signature.asc     Description: This is a digitally signed message part

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

According to its self-reported version, Cisco Web Security Appliance (WSA) is affected by a vulnerability in Server Name Identification (SNI) request filtering that allows an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
262734	Linux Distros Unpatched Vulnerability : CVE-2021-34749	Nessus	Misc.	high
171628	Debian DSA-5354-1 : snort - security update	Nessus	Debian Local Security Checks	high
171378	Debian dla-3317 : snort - security update	Nessus	Debian Local Security Checks	high
152812	Cisco Web Security Appliance (WSA) Server Name Identification Data Exfiltration (cisco-sa-sni-data-exfil-mFgzXqLN)	Nessus	CISCO	high

Detections

Analytics

CVE-2021-34749

high

Tenable Plugins

high

high

high

high