CVE Vulnerabilities

CVE-2014-1776

Use After Free

Published: Apr 27, 2014 | Modified: Oct 12, 2018
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
10 HIGH
AV:N/AC:L/Au:N/C:C/I:C/A:C
RedHat/V2
RedHat/V3
Ubuntu

Use-after-free vulnerability in Microsoft Internet Explorer 6 through 11 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via vectors related to the CMarkup::IsConnectedToPrimaryMarkup function, as exploited in the wild in April 2014. NOTE: this issue originally emphasized VGX.DLL, but Microsoft clarified that VGX.DLL does not contain the vulnerable code leveraged in this exploit. Disabling VGX.DLL is an exploit-specific workaround that provides an immediate, effective workaround to help block known attacks.

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Name Vendor Start Version End Version
Internet_explorer Microsoft 10 10
Internet_explorer Microsoft 8 8
Internet_explorer Microsoft 7 7
Internet_explorer Microsoft 6 6
Internet_explorer Microsoft 9 9
Internet_explorer Microsoft 11 11

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References