February 22, 2012

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Linux 2.6.39 Memory Handling Vulnerability

January 24, 2012 By

(LiveHacking.Com) – Exploits have started appearing that make it possible to gain root privileges on some versions of the Linux kernel due to a flaw in the  /proc/<pid>/mem handling. The vulnerability first came to light when Linus Torvalds released a Linux kernel update last week to fix the flaw and the subsequent analysis of the bug at  Nerdling Sapple.

The bug, which was discovered by Jüri Aedla, allows a local, unprivileged user to escalate their privileges. The problem is that write support to /proc/<pid>/mem was re-enabled in the kernel but with insufficient permissions checking. This means that all Linux kernels >=2.6.39 are vulnerable, up until the fix noted above.

Red Hat have released a small C program which will test a kernel to see if it is vulnerable. If you are not sure if you are running an affected kernel version compile and run the test from https://bugzilla.redhat.com/attachment.cgi?id=556461:

$ gcc -o test test.c
$ ./test
vulnerable

You can read Red Hat’s full security advisory here. Canonical, the makers of Ubuntu Linux, have also announced the release an update for Ubuntu 11.10. The fix can be applied using a standard system update followed by a reboot.

Filed Under: Linux, Linux, Open Source, Vulnerability Tagged With: , , ,

New Kernels for Ubuntu 10.04 LTS Fix Security Vulnerabilities

November 14, 2011 By

(LiveHacking.Com) - Unlike many Linux distributions, which are superseded almost daily, stable distributions from RedHat, CentOS and the Ubuntu LTS (Long Term Support) variants offer stability and a longer supported lifetime.

Ubuntu has just issued two new kernels for Ubuntu 10.04 LTS. The 10.04 release, which is available for both the server and the desktop, was released in April 2010 and will be supported until April 2013 (for the desktop) and until April 2015 for the server version.

The first new kernel is 2.6.32-35 a release of the default 2.6.32  kernel that used when Ubuntu 10.04 LTS was first released. The kernel has a number of security related fixes including:

  • The kernel incorrectly handled certain VLAN packets. On some systems, a remote attacker could send specially crafted traffic to crash the system, leading to a denial of service. (CVE-2011-1576)
  • Ecryptfs did not correctly check the origin of mount points. A local attacker could exploit this to trick the system into unmounting arbitrary mount points, leading to a denial of service. (CVE-2011-1833)
  • Taskstats did not enforce access restrictions. A local attacker could exploit this to read certain information, leading to a loss of privacy. (CVE-2011-2494)
  • /proc/PID/io did not enforce access restrictions. A local attacker could exploit this to read certain information, leading to a loss of privacy. (CVE-2011-2495)
  • The Bluetooth stack incorrectly handled certain L2CAP requests. If a system was using Bluetooth, a remote attacker could send specially crafted traffic to crash the system or gain root privileges. (CVE-2011-2497)
  • The EXT4 filesystem contained multiple off-by-one flaws. A local attacker could exploit this to crash the system, leading to a denial of service. (CVE-2011-2695)
  • The IPv6 stack used predictable fragment identification numbers. A remote attacker could exploit this to exhaust network resources, leading to a denial of service. (CVE-2011-2699)
  • The perf command looks for configuration files in the current directory. If a privileged user were tricked into running perf in a directory containing a malicious configuration file, an
  • attacker could run arbitrary commands and possibly gain privileges. (CVE-2011-2905)
  • Long symlinks were incorrectly handled on Be filesystems. A local attacker could exploit this with a malformed Be filesystem and crash the system, leading to a denial of service. (CVE-2011-2928)
  • The kernel incorrectly handled random sequence number generation. An attacker could use this flaw to possibly predict sequence numbers and inject packets. (CVE-2011-3188)
  • The CIFS client incorrectly handled certain large values. A remote attacker with a malicious server could exploit this to crash the system or possibly execute arbitrary code as the root user. (CVE-2011-3191)
The other new kernel, 2.6.38-12, is backport of kernel 2.6.38 from Ubuntu 11.04 to the standard repository. This kernel also contains a number of security updates.
Filed Under: Linux, Linux, Vulnerability Tagged With: , , ,

Exploit OOPS: Root Privileges on Linux

December 9, 2010 By

Security researcher Dan Rosenberg presents a small demo program which combines several security holes to obtaiLive Hacking Linux CDn root privileges on Linux systems on Full Disclosure Security mailing list.

He combined some existing vulnerabilities with the vulnerability discovered by Nelson Elhage in connection with the kernel’s thread management and troubleshooting routines (CVE-2010-4258).With this exploit, an attacker can potentially exploit an OOPS to write a null byte into the kernel’s memory area. [Read more...]

Filed Under: Linux, Open Source, Vulnerability Tagged With: , , , , ,

Red Hat: Vulnerability in OpenSSL

November 17, 2010 By

Red Hat released update packages for openssl that fix one security issue for Red Hat Enterprise Linux 6.The Red Hat Security Response Team has rated this update as having important security impact.

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols, as well as a full-strength, general purpose cryptography library.

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With reference to Red Hat support forum, A race condition flaw has been found in the OpenSSL TLS server extension parsing code, which could affect some multithreaded OpenSSL applications. Under certain specific conditions, it may be possible for a remote attacker to trigger this race condition and cause such an application to crash, or possibly execute arbitrary code with the permissions of the application. (CVE-2010-3864)

Note, this issue does not affect the Apache HTTP Server. Refer to Red Hat Bugzilla bug 649304 for more technical details on how to determine if your application is affected.

This update is recommended to all OpenSSL users. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at http://kbase.redhat.com/faq/docs/DOC-11259

Mr. Rob Hulswit has reported this bug to Red Hat.

Filed Under: Cryptography, Linux, Linux, Open Source, OpenSSL, Vulnerability Tagged With: , , ,

Hole in Linux kernel provides root rights – Update

September 21, 2010 By

A vulnerability in the 32-bit compatibility mode of the current Linux kernel (and previous versions) for 64-bit systems can be exploited to escalate privileges. For instance, attackers can break into a system and exploit a hole in the web server to get complete root (also known as superuser) rights or permissions for a victim’s system.

Read the full article here.

Source:[TheHSecurity]

Filed Under: Linux, Linux, Vulnerability