ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.

The remote CentOS Linux 9 host has packages installed that are affected by a vulnerability as referenced in the nginx-1.20.1-10.el9 build changelog.

  - Application Layer Protocol Confusion (CVE-2021-3618)

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

The version of vsftpd installed on the remote host is prior to 3.0.2-25. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2024-2431 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The version of nginx installed on the remote host is prior to 1.20.0-2. It is, therefore, affected by a vulnerability as referenced in the ALAS2NGINX1-2023-002 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote Ubuntu 20.04 LTS host has a package installed that is affected by a vulnerability as referenced in the USN-6379-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2023-018 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2023-099 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

  - NGINX Open Source before versions 1.23.2 and 1.22.1, NGINX Open Source Subscription before versions R2 P1     and R1 P1, and NGINX Plus before versions R27 P1 and R26 P1 have a vulnerability in the module     ngx_http_mp4_module that might allow a local attacker to corrupt NGINX worker memory, resulting in its     termination or potential other impact using a specially crafted audio or video file. The issue affects     only NGINX products that are built with the ngx_http_mp4_module, when the mp4 directive is used in the     configuration file. Further, the attack is possible only if an attacker can trigger processing of a     specially crafted audio or video file with the module ngx_http_mp4_module. (CVE-2022-41741)

  - NGINX Open Source before versions 1.23.2 and 1.22.1, NGINX Open Source Subscription before versions R2 P1     and R1 P1, and NGINX Plus before versions R27 P1 and R26 P1 have a vulnerability in the module     ngx_http_mp4_module that might allow a local attacker to cause a worker process crash, or might result in     worker process memory disclosure by using a specially crafted audio or video file. The issue affects only     NGINX products that are built with the module ngx_http_mp4_module, when the mp4 directive is used in the     configuration file. Further, the attack is possible only if an attacker can trigger processing of a     specially crafted audio or video file with the module ngx_http_mp4_module. (CVE-2022-41742)

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2023-019 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The version of nginx / vsftpd installed on the remote CBL Mariner 2.0 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the CVE-2021-3618 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by a vulnerability as referenced in the SUSE-SU-2022:4265-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by a vulnerability as referenced in the SUSE-SU-2022:4266-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by a vulnerability as referenced in the SUSE-SU-2022:4201-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

Note that Nessus has not tested for this issue 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-3203 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

  - NGINX Open Source before versions 1.23.2 and 1.22.1, NGINX Open Source Subscription before versions R2 P1     and R1 P1, and NGINX Plus before versions R27 P1 and R26 P1 have a vulnerability in the module     ngx_http_mp4_module that might allow a local attacker to corrupt NGINX worker memory, resulting in its     termination or potential other impact using a specially crafted audio or video file. The issue affects     only NGINX products that are built with the ngx_http_mp4_module, when the mp4 directive is used in the     configuration file. Further, the attack is possible only if an attacker can trigger processing of a     specially crafted audio or video file with the module ngx_http_mp4_module. (CVE-2022-41741)

  - NGINX Open Source before versions 1.23.2 and 1.22.1, NGINX Open Source Subscription before versions R2 P1     and R1 P1, and NGINX Plus before versions R27 P1 and R26 P1 have a vulnerability in the module     ngx_http_mp4_module that might allow a local attacker to cause a worker process crash, or might result in     worker process memory disclosure by using a specially crafted audio or video file. The issue affects only     NGINX products that are built with the module ngx_http_mp4_module, when the mp4 directive is used in the     configuration file. Further, the attack is possible only if an attacker can trigger processing of a     specially crafted audio or video file with the module ngx_http_mp4_module. (CVE-2022-41742)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:4192-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES12 / SLES_SAP12 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:3888-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2022-2022-172 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2022-2022-171 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:3457-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:3458-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES12 / SLES_SAP12 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:3383-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote SUSE Linux SLES15 / SLES_SAP15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2022:3320-1 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote Ubuntu 22.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-5371-2 advisory.

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 21.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5371-1 advisory.

  - An issue was discovered in OpenResty before 1.15.8.4. ngx_http_lua_subrequest.c allows HTTP request     smuggling, as demonstrated by the ngx.location.capture API. (CVE-2020-11724)

  - ngx_http_lua_module (aka lua-nginx-module) before 0.10.16 in OpenResty allows unsafe characters in an     argument when using the API to mutate a URI, or a request or response header. (CVE-2020-36309)

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

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

According to the versions of the nginx package installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - NGINX before 1.13.6 has a buffer overflow for years that exceed four digits, as demonstrated by a file     with a modification date in 1969 that causes an integer overflow (or a false modification date far in the     future), when encountered by the autoindex module. (CVE-2017-20005)

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

  - A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP     packets from the DNS server to cause 1-byte memory overwrite, resulting in worker process crash or     potential other impact. (CVE-2021-23017)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the nginx packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the nginx packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - NGINX before 1.13.6 has a buffer overflow for years that exceed four digits, as demonstrated by a file     with a modification date in 1969 that causes an integer overflow (or a false modification date far in the     future), when encountered by the autoindex module. (CVE-2017-20005)

  - ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing     different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A     MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one     subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-     protocol attacks may be possible where the behavior of one protocol service may compromise the other at     the application layer. (CVE-2021-3618)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
191321	CentOS 9 : nginx-1.20.1-10.el9	Nessus	CentOS Local Security Checks	high
189322	Amazon Linux 2 : vsftpd (ALAS-2024-2431)	Nessus	Amazon Linux Local Security Checks	high
181990	Amazon Linux 2 : nginx (ALASNGINX1-2023-002)	Nessus	Amazon Linux Local Security Checks	high
181543	Ubuntu 20.04 LTS : vsftpd vulnerability (USN-6379-1)	Nessus	Ubuntu Local Security Checks	high
173174	Amazon Linux 2023 : sendmail, sendmail-cf, sendmail-milter (ALAS2023-2023-018)	Nessus	Amazon Linux Local Security Checks	high
173141	Amazon Linux 2023 : nginx, nginx-all-modules, nginx-core (ALAS2023-2023-099)	Nessus	Amazon Linux Local Security Checks	high
173128	Amazon Linux 2023 : vsftpd (ALAS2023-2023-019)	Nessus	Amazon Linux Local Security Checks	high
172913	CBL Mariner 2.0 Security Update: nginx / vsftpd (CVE-2021-3618)	Nessus	MarinerOS Local Security Checks	high
168305	SUSE SLES15 Security Update : nginx (SUSE-SU-2022:4265-1)	Nessus	SuSE Local Security Checks	high
168297	SUSE SLES15 Security Update : nginx (SUSE-SU-2022:4266-1)	Nessus	SuSE Local Security Checks	high
168178	SUSE SLES15 Security Update : nginx (SUSE-SU-2022:4201-1)	Nessus	SuSE Local Security Checks	high
168171	Debian DLA-3203-1 : nginx - LTS security update	Nessus	Debian Local Security Checks	high
168166	SUSE SLES15 Security Update : nginx (SUSE-SU-2022:4192-1)	Nessus	SuSE Local Security Checks	high
167067	SUSE SLES12 Security Update : vsftpd (SUSE-SU-2022:3888-1)	Nessus	SuSE Local Security Checks	high
167013	Amazon Linux 2022 : (ALAS2022-2022-172)	Nessus	Amazon Linux Local Security Checks	high
167002	Amazon Linux 2022 : (ALAS2022-2022-171)	Nessus	Amazon Linux Local Security Checks	high
165565	SUSE SLES15 Security Update : vsftpd (SUSE-SU-2022:3457-1)	Nessus	SuSE Local Security Checks	high
165563	SUSE SLES15 Security Update : vsftpd (SUSE-SU-2022:3458-1)	Nessus	SuSE Local Security Checks	high
165492	SUSE SLES12 Security Update : vsftpd (SUSE-SU-2022:3383-1)	Nessus	SuSE Local Security Checks	high
165294	SUSE SLES15 Security Update : vsftpd (SUSE-SU-2022:3320-1)	Nessus	SuSE Local Security Checks	high
160309	Ubuntu 22.04 LTS : nginx vulnerability (USN-5371-2)	Nessus	Ubuntu Local Security Checks	high
159690	Ubuntu 16.04 ESM / 18.04 LTS / 20.04 LTS : nginx vulnerabilities (USN-5371-1)	Nessus	Ubuntu Local Security Checks	high
154391	EulerOS 2.0 SP3 : nginx (EulerOS-SA-2021-2599)	Nessus	Huawei Local Security Checks	critical
153726	EulerOS 2.0 SP5 : nginx (EulerOS-SA-2021-2513)	Nessus	Huawei Local Security Checks	high
153608	EulerOS 2.0 SP8 : nginx (EulerOS-SA-2021-2476)	Nessus	Huawei Local Security Checks	critical

Detections

Analytics

CVE-2021-3618

high

Tenable Plugins

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high

critical

high

critical