Przed chwilą się dowiedzieliśmy, że nergal (AKA Rafał Wojtczuk) przygotował patcha na kernel 2.2.19. Poprawki dołączane są do OpenWalla, któremu warto się od czasu do czasu przyglądać. Patch łata (po polsku: Łata łata) błąd związany z ptrace oraz jedną z możliwości wykonania lokalnego DOSa. Problem z ptrace nie dotyczy osób, które skorzystały z modułu noptrace.o, który znalazłem na kilku serwerach.
Pełniejszy opis błędów zamieszczam poniżej, a patch znajdziecie na tej stronie.
2001/10/18 kernel SECURITY FIX Severity: low to high, local, active A new revision of the Openwall Linux kernel patch, 2.2.19-ow3, is now available. It contains fixes for two Linux kernel vulnerabilities discovered by Rafal Wojtczuk <nergal at owl.openwall.com> and is strongly recommended for use with Owl. One of the vulnerabilities affected SUID/SGID execution by processes being traced with ptrace(2). It was possible to trick the kernel into recognizing an unsuspecting SUID root program as the (privileged) tracer process. Then, if that program would execute a program supplied by the malicious user (with the user's credentials), the user's program would inherit the ability to trace. Fortunately, there's no program that would meet all of the requirements for this attack in the default Owl install. However, certain supported non-default configurations of Owl are affected. In particular, if newgrp(1) is made available to untrusted users (which is a supported owl-control setting) or certain third-party software which contains SUID root binaries is installed, the vulnerability may become exploitable and result in a local root compromise. The other vulnerability allowed for an effective local DoS attack by causing the kernel to spend an almost arbitrary amount of time on dereferencing a single symlink, without giving a chance for processes to run.
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