CVE Vulnerabilities

CVE-2019-12525

Out-of-bounds Write

Published: Jul 11, 2019 | Modified: Apr 26, 2022
CVSS 3.x
9.8
CRITICAL
Source:
NVD
CVSS:3.1/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
4.3 MODERATE
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Ubuntu

An issue was discovered in Squid 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as domain, uri, and qop. Squid checks if this token’s value starts with a quote and ends with one. If so, it performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote (which would satisfy its requirements), leading to a memcpy of its length minus 1.

Weakness

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

Affected Software

Name Vendor Start Version End Version
Squid Squid-cache 4.0 4.7
Squid Squid-cache 3.3.9 3.5.28
Red Hat Enterprise Linux 7 RedHat squid-7:3.5.20-15.el7_8.1 *
Red Hat Enterprise Linux 8 RedHat squid:4-8020020200430095908.4cda2c84 *
Squid Ubuntu cosmic *
Squid Ubuntu devel *
Squid Ubuntu disco *
Squid Ubuntu trusty *
Squid Ubuntu upstream *
Squid3 Ubuntu bionic *
Squid3 Ubuntu esm-infra/xenial *
Squid3 Ubuntu precise/esm *
Squid3 Ubuntu trusty *
Squid3 Ubuntu upstream *
Squid3 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