CVE Vulnerabilities

CVE-2018-14600

Out-of-bounds Write

Published: Aug 24, 2018 | Modified: Aug 06, 2019
CVSS 3.x
9.8
CRITICAL
Source:
NVD
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
8.1 MODERATE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Ubuntu

An issue was discovered in libX11 through 1.6.5. The function XListExtensions in ListExt.c interprets a variable as signed instead of unsigned, resulting in an out-of-bounds write (of up to 128 bytes), leading to DoS or remote code execution.

Weakness

The software writes data past the end, or before the beginning, of the intended buffer.

Affected Software

Name Vendor Start Version End Version
Libx11 X.org * 1.6.5
Red Hat Enterprise Linux 7 RedHat gdm-1:3.28.2-16.el7 *
Red Hat Enterprise Linux 7 RedHat libX11-0:1.6.7-2.el7 *
Red Hat Enterprise Linux 7 RedHat libxkbcommon-0:0.7.1-3.el7 *
Red Hat Enterprise Linux 7 RedHat mesa-libGLw-0:8.0.0-5.el7 *
Red Hat Enterprise Linux 7 RedHat xorg-x11-drv-ati-0:19.0.1-2.el7 *
Red Hat Enterprise Linux 7 RedHat xorg-x11-drv-vesa-0:2.4.0-3.el7 *
Red Hat Enterprise Linux 7 RedHat xorg-x11-drv-wacom-0:0.36.1-3.el7 *
Red Hat Enterprise Linux 7 RedHat xorg-x11-server-0:1.20.4-7.el7 *
Libx11 Ubuntu bionic *
Libx11 Ubuntu devel *
Libx11 Ubuntu esm-infra/xenial *
Libx11 Ubuntu precise/esm *
Libx11 Ubuntu trusty *
Libx11 Ubuntu trusty/esm *
Libx11 Ubuntu upstream *
Libx11 Ubuntu xenial *

Potential Mitigations

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

  • Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

  • Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows.

  • For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

  • Consider adhering to the following rules when allocating and managing an application’s memory:

  • Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

  • Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64].

References