"Critical" Linux kernel flaws discovered

The three flaws could allow an unauthorised user to read or write to kernel memory locations or to access various resources in vulnerable systems, according to an advisory from SecurityFocus, the vendor neutral website that provides a wide range of security-related information, including a database of known software vulnerabilities.

The vulnerabilities could be exploited by malicious local users to cause denial-of-service (DoS) attacks, disclose potentially sensitive information, or gain "root" privileges to the operating system, according to the advisory.

The flaws affect all versions of the Linux kernel up to version 2.6.24.1, which contains a patch. Among the distributions impacted are the Debian GNU/Linux, Mandriva Linux One, Novell's SUSE, Red Hat's Enterprise, Turbolinux and Ubuntu.

According to an advisory from security vendor Secunia, the vulnerabilities impact a trio of functions in the system call fs/splice.c.

A hacker site, http://www.milw0rm.com, has released exploit code for the vulnerabilities. In addition, Core Security has developed a commercial exploit for the problems.

Systems administrators should update their kernels immediately to Linux kernel 2.6.24.1, according to security researchers.

These vulnerabilities follow in the wake of the announcement of earlier Linux kernel 2.6 flaws that could permit attackers to gain root system privileges they can use to steal data or mount denial-of-service on Linux-based systems.

Previously, Wojciech Purczynskiof of iSEC Security Research discovered multiple vulnerabilities in the vmsplice functions in the Linux kernel 2.6 OS.

These flaws he reported, are not being properly verified before being used to perform memory operations -- leaving them vulnerable to exploits that bypass security restrictions and enable attackers to elevate their system privileges.

"On Feb. 8, Wojciech Purczynskiof disclosed two flaws in the vmsplice (fs/splice.c) affecting the Linux kernel. The Linux kernel folks released updates. Neither of these flaws affected any Red Hat Enterprise Linux version,” Mark Cox, the head of Red Hat's security response team, told SCMagazineUS.com.

“On Feb. 9, an exploit was posted to milw0rm for a similar issue in vmsplice that wasn't [patched] by the fix for the two flaws above. This one did affect Red Hat Enterprise Linux 5 but not earlier RHEL."

He said Red Hat posted an update for that vulnerability on Tuesday. Cox noted that all three of the vulnerabilities “were written up by Secunia and others recently, which has added to the confusion and led people to think of them as new flaws."

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