D(HE)at Attack

What is the DHEAT Vulnerability?

Thu, 21 Aug 2025 00:00:00 +0000

Malicious actors have exploited the DHE cipher to take down servers. This D(HE)at Attack exploits the Diffie-Hellman key exchange protocol to DDOS the server it’s being run on. The client performing the attack on the server does not need to utilize many resources to do so.

How to harden OpenSSH server

Thu, 24 Apr 2025 00:00:00 +0000

Many people are often afraid to expose their SSH server to the internet, and they fall for a false sense of security by using the delusional security by obscurity of the likes of switching the port SSH listens on, which will hardly save you. Further, gimmicky things like fail2ban won’t really do much more other than waste resources.

ALAS-2024-727

Thu, 10 Oct 2024 00:00:00 +0000

Issue Overview: Validating the order of the public keys in the Diffie-Hellman Key Agreement Protocol, when an approved safe prime is used, allows remote attackers (from the client side) to trigger unnecessarily expensive server-side DHE modular-exponentiation calculations. The client may cause asymmetric resource consumption. 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 and validate the order of the public key. (CVE-2024-41996)

IT-Sicherheit: UNIX und Windows bedroht - Update für IT-Sicherheitshinweis zu Diffie-Hellman Implementierungen (Risiko: mittel)

Wed, 02 Oct 2024 00:00:00 +0000

Wie das BSI aktuell meldet, hat die IT-Sicherheitswarnung bezüglich einer bekannten Schwachstelle für Diffie-Hellman Implementierungen ein Update erhalten. Wie sich betroffene Nutzer verhalten sollten, erfahren Sie hier.

Security update for openssl-3

Tue, 01 Oct 2024 00:00:00 +0000

CVE-2024-41996: Validating the order of the public keys in the Diffie-Hellman Key Agreement Protocol, when an approved safe prime is used, allows remote attackers to trigger expensive server-side DHE (bsc#1230698)

How Diffie-Hellman Key Exchange can Cause Availability Issues

Mon, 09 Sep 2024 00:00:00 +0000

The Diffie-Hellman key exchange is a cryptographic protocol that allows parties to establish a shared secret over an insecure channel. The security of this key exchange is based on the difficulty of the Discrete Logarithm Problem (DLP) in a given group, such as the multiplicative group of integers modulo a prime number p.

Release 1.30.0-gke.1930

Thu, 29 Aug 2024 00:00:00 +0000

Google Distributed Cloud (software only) for VMware 1.30.0-gke.1930 is now available for download. To upgrade, see Upgrade a cluster or a node pool. Google Distributed Cloud 1.30.0-gke.1930 runs on Kubernetes v1.30.3-gke.200.

CVE-2024-41996

Mon, 26 Aug 2024 00:00:00 +0000

A vulnerability was found in the Diffie-Hellman Ephemeral (DHE) Key Agreement Protocol, where a malicious client can exploit the server’s public key validation process. By forcing the server to use DHE and validating the order of public keys, the client can trigger expensive server-side modular exponentiation calculations. This issue results in asymmetric resource consumption, potentially leading to a denial of service (DoS) attack by overwhelming the server with computationally intensive operations.

CVE-2024-41996

Mon, 26 Aug 2024 00:00:00 +0000

Validating the order of the public keys in the Diffie-Hellman Key Agreement Protocol, when an approved safe prime is used, allows remote attackers (from the client side) to trigger unnecessarily expensive server-side DHE modular-exponentiation calculations. The client may cause asymmetric resource consumption. 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 and validate the order of the public key.

CVE-2024-41996

Mon, 26 Aug 2024 00:00:00 +0000

D(HE)at Attack – 20-Yr-old Flaw Let Attackers Exploit Diffie-Hellman Protocol To Over-Heat Your CPU

Mon, 26 Aug 2024 00:00:00 +0000

Researchers uncovered a new type of denial-of-service (DoS) attack, known as the D(HE)at attack, exploits the computational demands of the Diffie-Hellman key agreement protocol, particularly its ephemeral variant (DHE), to overwhelm servers with minimal effort from the attacker.

USN-6854-1: OpenSSL vulnerability

Thu, 27 Jun 2024 00:00:00 +0000

OpenSSL could be made to consume resources and cause long delays if it processed certain input.

An Analysis of the DHEat DoS Against SSH in Cloud Environments

Tue, 23 Apr 2024 00:00:00 +0000

The DHEat denial-of-service vulnerability involves sending a large number of Diffie-Hellman (DH) public keys to a peer, causing it to perform many unnecessary modular exponentiations and wasting CPU resources (in fact, the attacker can simply send random numbers instead of real DH keys to avoid incurring the computational penalty themselves).

v3.2.0 Release

Mon, 22 Apr 2024 00:00:00 +0000

Added implementation of the DHEat denial-of-service attack (see --dheat option; CVE-2002-20001).

0.12.2 Changelog

Thu, 11 Jan 2024 00:00:00 +0000

Checker for well-known SSH vulnerabilities: Sweet32 attack, Anonymous Diffie-Hellman, NULL encryption, RC4, Non-Forward-Secret, Early SSH version, Weak Diffie-Hellman, DHEat attack, Terrapin attack

D(HE)at: A Practical Denial-of-Service Attack on the Finite Field Diffie–Hellman Key Exchange

Mon, 25 Dec 2023 00:00:00 +0000

S. Pfeiffer and N. Tihanyi, “D(HE)at: A Practical Denial-of-Service Attack on the Finite Field Diffie–Hellman Key Exchange,” in IEEE Access, vol. 12, pp. 957-980, 2024, doi: 10.1109/ACCESS.2023.3347422.

SA-2023-059 - DHEat attack (CVE-2002-20001)

Tue, 05 Dec 2023 00:00:00 +0000

The Diffie-Hellman Key Agreement Protocol enables remote attackers to send arbitrary numbers without public keys, triggering costly server-side DHE modular-exponentiation calculations. This attack requires minimal CPU resources and bandwidth, and may be more disruptive in cases where clients require server selection of largest supported key size.

Diffie-Hellman Ephemeral Key Exchange DoS Vulnerability (SSL/TLS, D(HE)ater)

Fri, 15 Sep 2023 00:00:00 +0000

The so-called DHEat Attack affects cryptographic protocols using the Diffie Hellman key exchange (incl. TLS). According to its authors, it exploits a potocol particularity that may allow attackers to perform a DoS attack “with a low-bandwidth network connection without authentication, privilege, or user interaction.”

0.8.4 Changelog

Sun, 22 Jan 2023 00:00:00 +0000

Checker for well-known TLS vulnerabilities: Anonymous Diffie-Hellman, DHEat attack, DROWN attack, Early TLS version, Export grade ciphers, FREAK attack, Logjam attack, Lucky Thirteen attack, NULL encryption, Non-Forward-Secret, RC4, Sweet32 attack

DHE Vulnerability of CVE 2022-40735

Thu, 08 Dec 2022 00:00:00 +0000

Customers have asked about CVE 2022-40735 and whether they are vulnerable as users of wolfSSL. The short is answer is: No. But, there are ways that you can put yourself at risk. Let’s delve into the CVE and how best to protect yourself from attacks like this.

CVE-2022-40735

Mon, 14 Nov 2022 00:00:00 +0000

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.

NVD - CVE-2022-40735

Mon, 14 Nov 2022 00:00:00 +0000

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.

SSA-506569: Multiple Vulnerabilities in SCALANCE W1750D

Tue, 08 Nov 2022 00:00:00 +0000

The SCALANCE W1750D device contains multiple vulnerabilities that could allow an attacker to inject commands or exploit buffer overflow vulnerabilities which could lead to denial of service, unauthenticated remote code execution or stored XSS. Siemens has released updates for the affected products and recommends to update to the latest versions.

Configuring Supported TLS Groups in OpenSSL

Wed, 12 Oct 2022 00:00:00 +0000

The configuration of supported groups in TLS servers is important to limit the resource consumption of the TLS handshakes performed by the server. This blog post should give system administrators a few useful hints on how to configure the OpenSSL library and two of the most used open source HTTP servers which use the OpenSSL library for supporting the HTTPS protocol. The CVE-2002-20001 (a.k.a DHEat attack) vulnerability inherent to the support of the Diffie-Hellman (DH) and Elliptic Curve Diffie-Hellman (ECDH) key exchanges in TLS and other protocols provides a way for an attacker to cause high CPU usage on servers with relatively low effort on the client side.

Diffie-Hellman Key Agreement Protocol vulnerability for Reflection for Secure IT for UNIX

Fri, 12 Aug 2022 00:00:00 +0000

Mitigation for the vulnerability referenced in CVE-2002-20001

K83120834: Diffie-Hellman key agreement protocol weaknesses CVE-2002-20001 & CVE-2022-40735

Thu, 19 May 2022 00:00:00 +0000

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.

Security Vulnerability: DHEater aka CVE-2002-20001

Thu, 19 May 2022 00:00:00 +0000

Security researchers from Balasys have published a new attack on Diffie-Hellman key exchange which allows remote attackers to attack network facing SSL / TLS / HTTPS / SSH services leading to excessive compute time usage even by sending small amounts of network traffic even before authentication. All applications on SUSE Linux Enterprise are affected that have DHE enabled. The Diffie-Hellman Epheremal key exchange is usually configured by default to provide perfect forward secrecy.

AOS-CX Switches Multiple Vulnerabilities

Tue, 22 Feb 2022 00:00:00 +0000

Aruba has released updates for wired switch products running AOS-CX that address multiple security vulnerabilities.

NVD - CVE-2002-20001

Thu, 11 Nov 2021 00:00:00 +0000

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.

D(HE)ater