ExecutableStacks

Differences between revisions 17 and 18
⇤ ← Revision 17 as of 2009-08-05 17:24:01 →
Size: 2953
Editor: 89
Comment:
← Revision 18 as of 2009-08-05 21:02:27 → ⇥
Size: 2958
Editor: 89
Comment:
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
There are still some programs that have executable stack regions, which results in their being vulnerable to exploitation via stack memory. There are only a few very rare situations where executable stacks are actually desired, and are usually the result of lacking flags in assembly code or using nested functions (which are generally avoidable). There are still some programs that have executable stack regions, which results in their being vulnerable to exploitation via stack memory. There are only a few very rare situations where executable stacks are actually desired, the rest are usually the result of lacking flags in assembly code or using nested functions (which are generally avoidable).

There are still some programs that have executable stack regions, which results in their being vulnerable to exploitation via stack memory. There are only a few very rare situations where executable stacks are actually desired, the rest are usually the result of lacking flags in assembly code or using nested functions (which are generally avoidable).

  • Detection: check an ELF binary: "readelf -lW $BIN | grep GNU_STACK" shows with "E" flag.

  • Information: Gentoo write-up about exec stack handling: http://www.gentoo.org/proj/en/hardened/gnu-stack.xml

  • Potential Solutions:

    • fix assembly source by adding flags to assembler: .section        .note.GNU-stack, "", @progbits

    • fix compiler's default when encountering unmarked assembly: -Wl,-z,noexecstack will change the behavior of compiler's asm-without-stack-markings defaults.

    • rework code to avoid using nested functions.
    • force markings into a safe state via "execstack -c $BINARY" during package build.

Main/Restricted Packages

Originally generated from the ELF files with executable stacks in Karmic main.

Fixed

Nested Functions

Uses Nested Functions which compiler generates as trampolines on the stack.

Trampolines

  • klibc (setjmp implementation)
  • kexec-tools (statically linked against klibc)

Shipped Precompiled Binary

  • fglrx-installer

  • nvidia

    • nvidia-graphics-drivers-173
    • nvidia-graphics-drivers-180
    • nvidia-graphics-drivers-71
    • nvidia-graphics-drivers-96

Unclassified

  • icon
  • john
  • link-grammar
  • mbr
  • memtest86+
  • openjdk-6

Fedora Patches

SecurityTeam/Roadmap/ExecutableStacks (last edited 2017-08-22 14:25:31 by jdstrand)