The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys, and trigger expensive server-side DHE modular-exponentiation calculations, aka a D(HE)at or D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive in cases where a client can require a server to select its largest supported key size. The basic attack scenario is that the client must claim that it can only communicate with DHE, and the server must be configured to allow DHE.

The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys, and trigger expensive server-side DHE modular- exponentiation calculations, aka a D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive in cases where a client can require a server to select its largest supported key size. The basic attack scenario is that the client must claim that it can only communicate with DHE, and the server must be configured to allow DHE.

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The version of F5 Networks BIG-IP installed on the remote host is prior to 16.1.4 / 17.1.0. It is, therefore, affected by multiple vulnerabilities as referenced in the K83120834 advisory.

    The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary     numbers that are actually not public keys, and trigger expensive server-side DHE modular-exponentiation     calculations, aka a D(HE)ater attack. The client needs very little CPU resources and network bandwidth.
    The attack may be more disruptive in cases where a client can require a server to select its largest     supported key size. The basic attack scenario is that the client must claim that it can only communicate     with DHE, and the server must be configured to allow DHE.(CVE-2002-20001)The Diffie-Hellman Key Agreement     Protocol allows use of long exponents that arguably make certain calculations unnecessarily expensive,     because the 1996 van Oorschot and Wiener paper found that (appropriately) short exponents can be used     when there are adequate subgroup constraints, and these short exponents can lead to less expensive     calculations than for long exponents. This issue is different from CVE-2002-20001 because it is based on     an observation about exponent size, rather than an observation about numbers that are not public keys. The     specific situations in which calculation expense would constitute a server-side vulnerability depend on     the protocol (e.g., TLS, SSH, or IKE) and the DHE implementation details. In general, there might be an     availability concern because of server-side resource consumption from DHE modular-exponentiation     calculations. Finally, it is possible for an attacker to exploit this vulnerability and CVE-2002-20001     together. (CVE-2022-40735)

Tenable has extracted the preceding description block directly from the F5 Networks BIG-IP security advisory.

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

ID	Name	Product	Family	Severity
501154	Siemens SCALANCE W1750D Uncontrolled Resource Consumption (CVE-2002-20001)	Tenable OT Security	Tenable.ot	high
161373	F5 Networks BIG-IP : Diffie-Hellman key agreement protocol weaknesses (K83120834)	Nessus	F5 Networks Local Security Checks	high

Detections

Analytics

CVE-2002-20001

high

Tenable Plugins

high

high