El Viernes pasado se anunciaron, en la lista de seguridad de debian, actualizaciones para el kernel, que solucionaba varias vulnerabilidades.
CVE-2009-0028 Chris Evans discovered a situation in which a child process can send an arbitrary signal to its parent. CVE-2009-0834 Roland McGrath discovered an issue on amd64 kernels that allows local users to circumvent system call audit configurations which filter based on the syscall numbers or argument details. CVE-2009-0835 Roland McGrath discovered an issue on amd64 kernels with CONFIG_SECCOMP enabled. By making a specially crafted syscall, local users can bypass access restrictions. CVE-2009-0859 Jiri Olsa discovered that a local user can cause a denial of service (system hang) using a SHM_INFO shmctl call on kernels compiled with CONFIG_SHMEM disabled. This issue does not affect prebuilt Debian kernels. CVE-2009-1046 Mikulas Patocka reported an issue in the console subsystem that allows a local user to cause memory corruption by selecting a small number of 3-byte UTF-8 characters. CVE-2009-1072 Igor Zhbanov reported that nfsd was not properly dropping CAP_MKNOD, allowing users to create device nodes on file systems exported with root_squash. CVE-2009-1184 Dan Carpenter reported a coding issue in the selinux subsystem that allows local users to bypass certain networking checks when running with compat_net=1. CVE-2009-1192 Shaohua Li reported an issue in the AGP subsystem they may allow local users to read sensitive kernel memory due to a leak of uninitialized memory. CVE-2009-1242 Benjamin Gilbert reported a local denial of service vulnerability in the KVM VMX implementation that allows local users to trigger an oops. CVE-2009-1265 Thomas Pollet reported an overflow in the af_rose implementation that allows remote attackers to retrieve uninitialized kernel memory that may contain sensitive data. CVE-2009-1337 Oleg Nesterov discovered an issue in the exit_notify function that allows local users to send an arbitrary signal to a process by running a program that modifies the exit_signal field and then uses an exec system call to launch a setuid application. CVE-2009-1338 Daniel Hokka Zakrisson discovered that a kill(-1) is permitted to reach processes outside of the current process namespace. CVE-2009-1439 Pavan Naregundi reported an issue in the CIFS filesystem code that allows remote users to overwrite memory via a long nativeFileSystem field in a Tree Connect response during mount.
Se publicaron dos exploits para explotar vulnerabildades de escalacion de provilegios local. Estos exploits se aprovechan de la funcion ptrace_attach() para ejecutar un codigo arbitrario que nos permita ejecutar una shell del tipo /bin/sh como root.
El primer exploit es el shoryuken, lo probé en distintas versiones del kernel de debian y archlinux, pudiendo ser explotada solo la version 2.6.26-1-686 de Debian 5.0, de forma aleatoria, es decir, hay veces que ejecuto el exploit y funciona y otras veces no. El segundo script fue probado por su autor en la version del kernel 2.6.29rc1 de Gentoo.
Estos exploits funcionan bajo situaciones especificas y no todos los sistemas son vulnerables.
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