• Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
MUST READ

The FBI warns that Scattered Spider is now targeting the airline sector

 | 

LapDogs: China-nexus hackers Hijack 1,000+ SOHO devices for espionage

 | 

Taking over millions of developers exploiting an Open VSX Registry flaw

 | 

OneClik APT campaign targets energy sector with stealthy backdoors

 | 

APT42 impersonates cyber professionals to phish Israeli academics and journalists

 | 

Kai West, aka IntelBroker, indicted for cyberattacks causing $25M in damages

 | 

Cisco fixed critical ISE flaws allowing Root-level remote code execution

 | 

U.S. CISA adds AMI MegaRAC SPx, D-Link DIR-859 routers, and Fortinet FortiOS flaws to its Known Exploited Vulnerabilities catalog

 | 

CitrixBleed 2: The nightmare that echoes the 'CitrixBleed' flaw in Citrix NetScaler devices

 | 

Hackers deploy fake SonicWall VPN App to steal corporate credentials

 | 

Mainline Health Systems data breach impacted over 100,000 individuals

 | 

Disrupting the operations of cryptocurrency mining botnets

 | 

Prometei botnet activity has surged since March 2025

 | 

The U.S. House banned WhatsApp on government devices due to security concerns

 | 

Russia-linked APT28 use Signal chats to target Ukraine official with malware

 | 

China-linked APT Salt Typhoon targets Canadian Telecom companies

 | 

U.S. warns of incoming cyber threats following Iran airstrikes

 | 

McLaren Health Care data breach impacted over 743,000 people

 | 

American steel giant Nucor confirms data breach in May attack

 | 

The financial impact of Marks & Spencer and Co-op cyberattacks could reach £440M

 | 
  • Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
  • Home
  • Breaking News
  • Hacking
  • Terrapin attack allows to downgrade SSH protocol security

Terrapin attack allows to downgrade SSH protocol security

Pierluigi Paganini January 02, 2024

Researchers discovered an SSH vulnerability, called Terrapin, that could allow an attacker to downgrade the connection’s security.

Security researchers from Ruhr University Bochum (Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk) discovered a vulnerability, called Terrapin (CVE-2023-48795, CVSS score 5.9), in the Secure Shell (SSH) cryptographic network protocol. An attacker can trigger the flaw to downgrade the connection’s security implemented by the protocol.

The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution.

Terrapin is a prefix truncation attack, it works by breaking the integrity of SSH’s secure channel.

“By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it.” reads the advisory published by the researchers. “The attack can be performed in practice, allowing an attacker to downgrade the connection’s security by truncating the extension negotiation message (RFC8308) from the transcript. The truncation can lead to using less secure client authentication algorithms and deactivating specific countermeasures against keystroke timing attacks in OpenSSH 9.5.”

The truncation may result in the utilization of less secure client authentication algorithms and the deactivation of specific countermeasures against keystroke timing attacks in OpenSSH 9.5.

To perform the Terrapin attack, a threat actor must be able to perform a MitM attack at the network layer. Another pre-requirement is that the connection must be secured by either ChaCha20-Poly1305 or CBC with Encrypt-then-MAC. 

The Terrapin attack could allow to intercept sensitive data or take over critical systems using administrator privileged access.

The following image shows the Terrapin attack.

Terrapin attack

“The attacker can drop the EXT_INFO message, used for negotiating several protocol extensions, without the client or server noticing it. Usually, packet deletion would be detected by the client when receiving the next binary packet sent by the server, as sequence numbers would mismatch.” continues the analysis. “To avoid this, an attacker injects an ignored packet during the handshake to offset the sequence numbers accordingly.”

The researchers published a full technical paper titled “Terrapin Attack: Breaking SSH Channel Integrity By Sequence Number Manipulation.”

The experts also published a simple console application on GitHub written in Go that can allow to determine whether an SSH server or client is vulnerable to the Terrapin attack.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, Terrapin attack)


facebook linkedin twitter

Hacking hacking news information security news IT Information Security Pierluigi Paganini Security Affairs Security News SSH Terrapin attack

you might also like

Pierluigi Paganini June 28, 2025
The FBI warns that Scattered Spider is now targeting the airline sector
Read more
Pierluigi Paganini June 28, 2025
LapDogs: China-nexus hackers Hijack 1,000+ SOHO devices for espionage
Read more

leave a comment

newsletter

Subscribe to my email list and stay
up-to-date!

    recent articles

    The FBI warns that Scattered Spider is now targeting the airline sector

    Cyber Crime / June 28, 2025

    LapDogs: China-nexus hackers Hijack 1,000+ SOHO devices for espionage

    Malware / June 28, 2025

    Taking over millions of developers exploiting an Open VSX Registry flaw

    Hacking / June 27, 2025

    OneClik APT campaign targets energy sector with stealthy backdoors

    Hacking / June 27, 2025

    APT42 impersonates cyber professionals to phish Israeli academics and journalists

    APT / June 27, 2025

    To contact me write an email to:

    Pierluigi Paganini :
    pierluigi.paganini@securityaffairs.co

    LEARN MORE

    QUICK LINKS

    • Home
    • Cyber Crime
    • Cyber warfare
    • APT
    • Data Breach
    • Deep Web
    • Digital ID
    • Hacking
    • Hacktivism
    • Intelligence
    • Internet of Things
    • Laws and regulations
    • Malware
    • Mobile
    • Reports
    • Security
    • Social Networks
    • Terrorism
    • ICS-SCADA
    • POLICIES
    • Contact me

    Copyright@securityaffairs 2024

    We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
    Cookie SettingsAccept All
    Manage consent

    Privacy Overview

    This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities...
    Necessary
    Always Enabled
    Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
    Non-necessary
    Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
    SAVE & ACCEPT