| Finding ID |
Severity |
Title |
Description |
|
V-268313
|
High |
AOS, when used as a VPN Gateway, must not accept certificates that have been revoked when using PKI for authentication. |
Situations may arise in which the certificate issued by a certificate authority (CA) may need to be revoked before the lifetime of the certificate expires (for example, when the certificate is known to have been compromised).
When an incoming Internet Key Exchange (IKE) session is initiated for a remote client... |
|
V-267001
|
High |
AOS, when used as an IPsec VPN Gateway, must use Internet Key Exchange (IKE) for IPsec VPN security associations (SAs). |
Without IKE, the SPI is manually specified for each security association. IKE peers will negotiate the encryption algorithm and authentication or hashing methods as well as generate the encryption keys.
An IPsec SA is established using either IKE or manual configuration. When using IKE, the security associations are established when... |
|
V-266985
|
High |
AOS, when used as an IPsec VPN Gateway, must use Advanced Encryption Standard (AES) encryption for the Internet Key Exchange (IKE) proposal to protect confidentiality of remote access sessions. |
Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session.
Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network.
AES is the Federal Information Processing Standard (FIPS)-validated cipher block... |
|
V-266982
|
High |
AOS, when used as an IPsec VPN Gateway, must specify Perfect Forward Secrecy (PFS) during Internet Key Exchange (IKE) negotiation. |
PFS generates each new encryption key independently from the previous key. Without PFS, compromise of one key will compromise all communications.
The phase 2 (Quick Mode) Security Association (SA) is used to create an IPsec session key. Hence, its rekey or key regeneration procedure is very important. The phase 2... |
|
V-267000
|
Medium |
AOS, when used as a VPN Gateway, must disable split-tunneling for remote client VPNs. |
Split tunneling would in effect allow unauthorized external connections, making the system more vulnerable to attack and to exfiltration of organizational information.
A VPN hardware or software client with split tunneling enabled provides an unsecured backdoor to the enclave from the internet. With split tunneling enabled, a remote client has... |
|
V-266999
|
Medium |
AOS, when used as a VPN Gateway, must be configured to route sessions to an intrusion detection and prevention system (IDPS) for inspection. |
Remote access devices, such as those providing remote access to network devices and information systems, that lack automated capabilities increase risk and make remote user access management difficult at best.
Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an... |
|
V-266998
|
Medium |
The Remote Access VPN Gateway must be configured to prohibit Point-to-Point Tunneling Protocol (PPTP) and Layer 2 Forwarding (L2F). |
PPTP and L2F are obsolete methods for implementing virtual private networks. Both protocols may be easy to use and readily available, but they have many well-known security issues and exploits. Encryption and authentication are both weak. |
|
V-266997
|
Medium |
AOS, when used as a VPN Gateway, must renegotiate the security association after 24 hours or less or as defined by the organization. |
When a VPN gateway creates an IPsec security association (SA), resources must be allocated to maintain the SA. These resources are wasted during periods of IPsec endpoint inactivity, which could result in the gateway's inability to create new SAs for other endpoints, thereby preventing new sessions from connecting.
The Internet... |
|
V-266996
|
Medium |
The Remote Access VPN Gateway must terminate remote access network connections after an organization-defined time period. |
This requirement is in response to the DOD Office of Inspector General Audit of Maintaining Cybersecurity in the Coronavirus Disease-2019 Telework Environment.
Best practice is to terminate inactive user sessions after a period; however, when setting timeouts to any VPN connection, the organization must consider the risk to the mission... |
|
V-266995
|
Medium |
The VPN Gateway must uniquely identify and authenticate organizational users (or processes acting on behalf of organizational users). |
To ensure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system.
Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and any processes acting on behalf of... |
|
V-266994
|
Medium |
The Remote Access VPN Gateway must use a separate authentication server (e.g., Lightweight Directory Access Protocol [LDAP], Remote Authentication Dial-In User Service [RADIUS], Terminal Access Controller Access-Control System+ [TACACS+] to perform user authentication. |
The VPN interacts directly with public networks and devices and should not contain user authentication information for all users. Authentication, Authorization, and Accounting (AAA) network security services provide the primary framework through which a network administrator can set up access control and authorization on network points of entry or network... |
|
V-266993
|
Medium |
AOS, when used as a VPN Gateway, must limit the number of concurrent sessions for user accounts to one or to an organization-defined number. |
VPN gateway management includes the ability to control the number of users and user sessions that utilize a VPN gateway. Limiting the number of allowed users and sessions per user is helpful in limiting risks related to denial-of-service attacks.
This requirement addresses concurrent sessions for information system accounts and does... |
|
V-266992
|
Medium |
AOS, when used as a VPN Gateway, must ensure inbound and outbound traffic is configured with a security policy in compliance with information flow control policies. |
Unrestricted traffic may contain malicious traffic, which poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a network, which uses bandwidth and other resources.
VPN traffic received from another enclave with different security policy or level of trust must not bypass being inspected... |
|
V-266991
|
Medium |
For site-to-site VPN implementations using AOS, the Layer 2 Tunneling Protocol (L2TP) must be blocked or denied at the security boundary with the private network so unencrypted L2TP packets cannot traverse into the private network of the enclave. |
Unlike Generic Routing Encapsulation (GRE) (a simple encapsulating header), L2TP is a full-fledged communications protocol with control channel, data channels, and a robust command structure. In addition to Point-to-Point Protocol (PPP), other link layer types (called pseudowires) can be and are defined for delivery in L2TP by separate Internet Engineering... |
|
V-266989
|
Medium |
The Remote Access VPN Gateway and/or client must display the Standard Mandatory DOD Notice and Consent Banner before granting remote access to the network. |
|
|
V-266988
|
Medium |
AOS, when used as a VPN Gateway, must authenticate all network-connected endpoint devices before establishing a connection. |
Without authenticating devices, unidentified or unknown devices may be introduced, thereby facilitating malicious activity.
For distributed architectures (e.g., service-oriented architectures), the decisions regarding the validation of authentication claims may be made by services separate from the services acting on those decisions. In such situations, it is necessary to provide authentication... |
|
V-266987
|
Medium |
AOS, when used as a VPN Gateway, must uniquely identify all network-connected endpoint devices before establishing a connection. |
Without identifying devices, unidentified or unknown devices may be introduced, thereby facilitating malicious activity.
For distributed architectures (e.g., service-oriented architectures), the decisions regarding the validation of identification claims may be made by services separate from the services acting on those decisions. In such situations, it is necessary to provide the... |
|
V-266986
|
Medium |
AOS, when used as a VPN Gateway, must use an approved Commercial Solution for Classified (CSfC) when transporting classified traffic across an unclassified network. |
Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data.
The National Security Agency/Central Security Service's (NSA/CSS) CSfC program enables commercial products to be used in layered solutions to protect classified National Security Systems (NSS) data. Currently, Suite B cryptographic algorithms are specified by... |
|
V-266984
|
Medium |
AOS, when used as a VPN Gateway and using public key infrastructure (PKI)-based authentication, must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor. |
Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted. To meet this requirement, the information system must create trusted channels between itself and remote trusted authorized IT product (e.g., syslog server) entities that protect the confidentiality... |
|
V-266983
|
Medium |
AOS, when used as a VPN Gateway, must be configured to use IPsec with SHA-2 at 384 bits or greater for hashing to protect the integrity of remote access sessions. |
Without strong cryptographic integrity protections, information can be altered by unauthorized users without detection.
SHA-1 is considered a compromised hashing standard and is being phased out of use by industry and government standards. DOD systems must not be configured to use SHA-1 for integrity of remote access sessions.
The remote... |
|
V-266990
|
Low |
AOS, when used as a VPN Gateway, must terminate all network connections associated with a communications session at the end of the session. |
Idle Transmission Control Protocol (TCP) sessions can be susceptible to unauthorized access and hijacking attacks. By default, routers do not continually test whether a previously connected TCP endpoint is still reachable. If one end of a TCP connection idles out or terminates abnormally, the opposite end of the connection may... |
