CVE Vulnerabilities

CVE-2013-2004

Improper Restriction of Operations within the Bounds of a Memory Buffer

Published: Jun 15, 2013 | Modified: Jun 21, 2013
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
6.8 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P
RedHat/V2
1.8 LOW
AV:A/AC:H/Au:N/C:N/I:N/A:P
RedHat/V3
Ubuntu

The (1) GetDatabase and (2) _XimParseStringFile functions in X.org libX11 1.5.99.901 (1.6 RC1) and earlier do not restrict the recursion depth when processing directives to include files, which allows X servers to cause a denial of service (stack consumption) via a crafted file.

Weakness

The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer.

Affected Software

Name Vendor Start Version End Version
Libx11 X * 1.5.99.901 (including)
Libx11 X 1.5.0 (including) 1.5.0 (including)
Red Hat Enterprise Linux 6 RedHat libdmx-0:1.1.3-3.el6 *
Red Hat Enterprise Linux 6 RedHat libX11-0:1.6.0-2.2.el6 *
Red Hat Enterprise Linux 6 RedHat libxcb-0:1.9.1-2.el6 *
Red Hat Enterprise Linux 6 RedHat libXcursor-0:1.1.14-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXext-0:1.3.2-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXfixes-0:5.0.1-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXi-0:1.7.2-2.2.el6 *
Red Hat Enterprise Linux 6 RedHat libXinerama-0:1.1.3-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXp-0:1.0.2-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXrandr-0:1.4.1-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXrender-0:0.9.8-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXres-0:1.0.7-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXt-0:1.1.4-6.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXtst-0:1.2.2-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXv-0:1.0.9-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXvMC-0:1.0.8-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXxf86dga-0:1.1.4-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat libXxf86vm-0:1.1.3-2.1.el6 *
Red Hat Enterprise Linux 6 RedHat xcb-proto-0:1.8-3.el6 *
Red Hat Enterprise Linux 6 RedHat xkeyboard-config-0:2.11-1.el6 *
Red Hat Enterprise Linux 6 RedHat xorg-x11-proto-devel-0:7.7-9.el6 *
Red Hat Enterprise Linux 6 RedHat xorg-x11-xtrans-devel-0:1.3.4-1.el6 *
Libx11 Ubuntu devel *
Libx11 Ubuntu lucid *
Libx11 Ubuntu precise *
Libx11 Ubuntu quantal *
Libx11 Ubuntu raring *
Libx11 Ubuntu upstream *

Extended Description

Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data. As a result, an attacker may be able to execute arbitrary code, alter the intended control flow, read sensitive information, or cause the system to crash.

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.

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

  • D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

  • 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]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

  • For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

  • Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

  • For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

References