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OpenSSH Now Encrypts Secret Keys in Memory Against Side-Channel Attacks

OpenSSH Now Encrypts Secret Keys in Memory Against Side-Channel Attacks

June 22, 2019Mohit Kumar
In recent years, several groups of cybersecurity researchers have disclosed dozens of memory side-channel vulnerabilities in modern processors and DRAM s, like Rowhammer , RAMBleed , Spectre, and Meltdown . Have you ever noticed they all had at least one thing in common? That's OpenSSH. As a proof-of-concept, many researchers demonstrated their side-channel attacks against OpenSSH application installed on a targeted computer, where an unprivileged attacker-owned process exploits memory read vulnerabilities to steal secret SSH private keys from the restricted memory regions of the system. That's possible because OpenSSH has an agent that keeps a copy of your SSH key in the memory so that you don't have to type your passphrase every time you want to connect to the same remote server. However, modern operating systems by default store sensitive data, including encryption keys and passwords, in the kernel memory which can not be accessed by user-level privileged p
PuTTY Releases Important Software Update to Patch 8 High-Severity Flaws

PuTTY Releases Important Software Update to Patch 8 High-Severity Flaws

March 20, 2019Wang Wei
The popular SSH client program PuTTY has released the latest version of its software that includes security patches for 8 high-severity security vulnerabilities. PuTTY is one of the most popular and widely used open-source client-side programs that allows users to remotely access computers over SSH, Telnet, and Rlogin network protocols. Almost 20 months after releasing the last version of its software, the developers of PuTTY earlier this week released the latest version 0.71 for Windows and Unix operating systems. According to an advisory available on its website, all previous versions of the PuTTY software have been found vulnerable to multiple security vulnerabilities that could allow a malicious server or a compromised server to hijack client's system in different ways. Here below I have listed all 8 vulnerabilities with brief information that PuTTY 0.71 has patched: 1) Authentication Prompt Spoofing — Since PuTTY doesn't have a way to indicate whether a piec
Libssh Releases Update to Patch 9 New Security Vulnerabilities

Libssh Releases Update to Patch 9 New Security Vulnerabilities

March 19, 2019Wang Wei
Libssh2, a popular open source client-side C library implementing the SSHv2 protocol, has released the latest version of its software to patch a total of nine security vulnerabilities. The Libssh2 library is available for all major distributors of the Linux operating systems, including Ubuntu, Red Hat, Debian, and also comes bundled within some distributions and software as a default library. According to an  advisory published Monday, all the below listed vulnerabilities that were patched with the release of libssh2 version 1.8.1 lead to memory corruption issues which could result in arbitrary code execution on a client system in certain circumstances. Here's the list of security vulnerabilities patched in Libssh: 1. CVE-2019-3855: Possible integer overflow in transport read that could lead to an out-of-bounds write. A malicious server, or a remote attacker who compromises an SSH server, could send a specially crafted packet which could result in executing malicious
36-Year-Old SCP Clients' Implementation Flaws Discovered

36-Year-Old SCP Clients' Implementation Flaws Discovered

January 15, 2019Mohit Kumar
A set of 36-year-old vulnerabilities has been uncovered in the Secure Copy Protocol (SCP) implementation of many client applications that can be exploited by malicious servers to overwrite arbitrary files in the SCP client target directory unauthorizedly. Session Control Protocol (SCP), also known as secure copy, is a network protocol that allows users to securely transfer files between a local host and a remote host using RCP (Remote Copy Protocol) and SSH protocol. In other terms, SCP, which dates back to 1983, is a secure version of RCP that uses authentication and encryption of SSH protocol to transfer files between a server and a client. Discovered by Harry Sintonen, one of F-Secure's Senior Security Consultants, the vulnerabilities exist due to poor validations performed by the SCP clients, which can be abused by malicious servers or man-in-the-middle (MiTM) attackers to drop or overwrite arbitrary files on the client's system. "Many scp clients fail to ver
LibSSH Flaw Allows Hackers to Take Over Servers Without Password

LibSSH Flaw Allows Hackers to Take Over Servers Without Password

October 17, 2018Mohit Kumar
A four-year-old severe vulnerability has been discovered in the Secure Shell (SSH) implementation library known as Libssh that could allow anyone to completely bypass authentication and gain unfettered administrative control over a vulnerable server without requiring a password. The security vulnerability, tracked as CVE-2018-10933 , is an authentication-bypass issue that was introduced in Libssh version 0.6 released earlier 2014, leaving thousands of enterprise servers open to hackers for the last four years. But before you get frightened, you should know that neither the widely used OpenSSH nor Github's implementation of libssh was affected by the vulnerability. The vulnerability resides due to a coding error in Libssh and is "ridiculously simple" to exploit. According to a security advisory published Tuesday, all an attacker needs to do is sending an "SSH2_MSG_USERAUTH_SUCCESS" message to a server with an SSH connection enabled when it expects an &
Wikileaks Unveils CIA Implants that Steal SSH Credentials from Windows & Linux PCs

Wikileaks Unveils CIA Implants that Steal SSH Credentials from Windows & Linux PCs

July 06, 2017Swati Khandelwal
WikiLeaks has today published the 15th batch of its ongoing Vault 7 leak , this time detailing two alleged CIA implants that allowed the agency to intercept and exfiltrate SSH (Secure Shell) credentials from targeted Windows and Linux operating systems using different attack vectors. Secure Shell or SSH is a cryptographic network protocol used for remote login to machines and servers securely over an unsecured network. Dubbed BothanSpy — implant for Microsoft Windows Xshell client, and Gyrfalcon — targets the OpenSSH client on various distributions of Linux OS, including CentOS, Debian, RHEL (Red Hat), openSUSE and Ubuntu. Both implants steal user credentials for all active SSH sessions and then sends them to a CIA-controlled server. BothanSpy — Implant for Windows OS BothanSpy is installed as a Shellterm 3.x extension on the target machine and only works if Xshell is running on it with active sessions. Xshell is a powerful terminal emulator that supports SSH, SFTP,
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