Linux vulnerability leaves thousands open to DNS attack

Buffer overflow glibc bug affects virtually all versions of the OS

An enormous vulnerability in Linux that could put potentially all computers running the operating system at risk has been uncovered by Google and Red Hat.

The stack-based buffer overflow bug, which has been given the designation CVE-2015-7547, affects all versions of glibc from version 2.9 onwards.

According to Google's analysis, the glibc DNS client side server can be subjected to a stack-based buffer overflow attack when the getaddrinfo() library function is used.

An attacker could use this vulnerability to carry out a remote code execution if a victim visits a malicious site, DNS server, or through a man-in-the-middle attack. What's more, Linux machines that have the bug are vulnerable to attack not only if they visit untrusted or compromised DNS servers, but simply if they try to resolve a hostname where that hostname's authoratitive DNS is an attacker.

Fermin J Serna, a staff security engineer, and Kevin Stadmeyer, a technical program manager, who both work for Google, said in a blog post that they managed to create a proof-of-concept exploit.

"The vectors to trigger this buffer overflow are very common and can include ssh, sudo, and curl. We are confident that the exploitation vectors are diverse and widespread," they said.

The bug is similar to the Ghost Linux vulnerability found in January 2015, which was also a remote code execution attack in glibc.

Commenting on the new vulnerability, Paul Farringdon, senior solution architect at Veracode, said: "Web application attacks remain one of the most frequent patterns in confirmed breaches [accounting] for up to 35 per cent in some industries according to the 2015 Verizon Data Breach Investigations Report."

"This type of finding underlines the need for organisations to be able to pinpoint known vulnerable components in their software as soon as the new exploit hits the news wires," he added.

A patch, created jointly by Red Hat and Google, is available here.

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