Severe Linux GHOST Flaw Spooks Out Computer Users

Duncan MacRae is former editor and now a contributor to TechWeekEurope. He previously edited Computer Business Review's print/digital magazines and CBR Online, as well as Arabian Computer News in the UAE.

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Critical vulnerability found in Linux systems gives attackers control without system credentials

A critical vulnerability in operating system Linux has been discovered, which allows attackers to remotely take control of an entire system without having any prior knowledge of system credentials.

The vulnerability, discovered by Qualys, a provider of cloud security and compliance solution, is in the Linux GNU C Library (glibc) and is known as GHOST (CVE-2015-0235), because it can be triggered by the gethostbyname functions. It impacts many systems built on Linux starting with glibc-2.2 released on November 10, 2000.

Left exposed

Qualys researchers also identified a number of factors that mitigate the impact of this bug including a fix released on May 21, 2013 between the releases of glibc-2.17 and glibc-2.18. Unfortunately, this fix was not classified as a security advisory and, as a result, most stable and long-term-support distributions were left exposed including – Debian 7 (wheezy), Red Hat Enterprise Linux 6 & 7, CentOS 6 & 7 and Ubuntu 12.04.

security vulnerability Shutterstock - © Andy Dean PhotographyQualys said its customers can detect GHOST by scanning with the Qualys Vulnerability Management (VM) cloud solution as QID 123191. This means that Qualys customers can get reports detailing their enterprise-wide exposure during their next scanning cycle, which allows them to get visibility into the impact within their organisation and efficiently track the
remediation progress of this serious vulnerability.

Wolfgang Kandek, chief technology officer for Qualys, said: “GHOST poses a remote code execution risk that makes it incredibly easy for an attacker to exploit a machine. For example, an attacker could send a simple email on a Linux-based system and automatically get complete access to that machine.”

“Given the sheer number of systems based on glibc, we believe this is a high severity vulnerability and should be addressed immediately. The best course of action to mitigate the risk is to apply a patch from your Linux vendor.”

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