A new found vulnerability known as GHOST (CVE-2015-0235) affects many systems built on Linux starting with glibc-2.2 as well as Debian 7 (wheezy), Red Hat Enterprise Linux 6 & 7, CentOS 6 & 7 and Ubuntu 12.04, and allows attackers to remotely take control of an entire system without having any prior knowledge of system credentials. The vulnerability is termed as GHOST because it lets the attacker take control of the victim’s system remotely by exploiting a buffer overflow bug in glibc’s gethostbyname( ) functions.
The year 2014 discovered three major vulnerabilities – Heartbleed, Shell Shock Hash bug and the Poodle bug. These major vulnerabilities have shaken the edifice of security havens. The Heart bleed bug made it possible for attackers to steal data from a server including the keys to decode any encrypted contents.
Shellshock a more serious bug made it possible for hackers to take control of millions of machines around the world quietly without notice. Another new breed of bug, Poodle, was found in a 15-year-old web encryption technology called SSL 3.0. SSL, which stands for Secure Sockets Layer, a technology that encrypts a user’s browsing session, making it difficult for anyone using the public Wi-Fi to eavesdrop. The Poodle bug makes it possible for hackers to hijack their victim’s browsing session and do things like take over their email, online banking, or social networking account.
This GHOST vulnerability affects almost all major Linux distributions, except a few such as Ubuntu 14.04. Millions of servers on the Internet contain this vulnerability.
As a buffer overflow bug, GHOST affects certain function calls in the Glibc library. The vulnerability allows a remote attacker to execute arbitrary code using these function calls that are used for DNS resolving, a common event. In exploiting this vulnerability, an attacker may trigger a buffer overflow by supplying an invalid hostname argument to an application that performs a DNS resolution. To eliminate the possibility of an exploit, the specific function calls, ‘glibc’ and ‘mscd’ is to be updated on the system using packages released by Linux updates.
Researchers at Veracode discovered that nearly 41% of enterprise applications using GNU C Library employ the Ghost-ridden ‘gethostbyname’ function. Veracode rates this vulnerability as highly ‘Critical’, as 80% of applications like financial transaction applications or application that access sensitive databases uses ‘glibc’ library and which could be victim of GHOST vulnerability. According to Veracode, the code that initiate network connection, log processing and mail or spam filtering can be vulnerable to GHOST as it uses gethostbyname( ); function.initiate network connection, log processing and mail or spam filtering can be vulnerable to GHOST as it uses gethostbyname( ) function.
Veracode found that 72% of applications which is written in C or C++ are potentially vulnerable to GHOST; applications written in Java, .NET, and PHP are also vulnerable to GHOST.
The easiest way to check for this vulnerability is to run the Aegify scanner on Linux hosted servers within the organization and in its external IT infrastructure. Patches are now available for resolving this vulnerability.
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