CVE-2018-8345 - Improper Control of Generation of Code ('Code Injection')

Severity

76%

Complexity

49%

Confidentiality

165%

A remote code execution vulnerability exists in Microsoft Windows that could allow remote code execution if a .LNK file is processed, aka "LNK Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers. This CVE ID is unique from CVE-2018-8346.

A remote code execution vulnerability exists in Microsoft Windows that could allow remote code execution if a .LNK file is processed, aka "LNK Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers. This CVE ID is unique from CVE-2018-8346.

CVSS 3.0 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: high. CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).

CVSS 2.0 Base Score 7.6. CVSS Attack Vector: network. CVSS Attack Complexity: high. CVSS Vector: (AV:N/AC:H/Au:N/C:C/I:C/A:C).

Demo Examples

Improper Control of Generation of Code ('Code Injection')

CWE-94

This example attempts to write user messages to a message file and allow users to view them.


               
}
echo "Message Saved!<p>\n";
include($MessageFile);

While the programmer intends for the MessageFile to only include data, an attacker can provide a message such as:


               
message=%3C?php%20system(%22/bin/ls%20-l%22);?%3E

which will decode to the following:


               
<?php system("/bin/ls -l");?>

The programmer thought they were just including the contents of a regular data file, but PHP parsed it and executed the code. Now, this code is executed any time people view messages.

Notice that XSS (CWE-79) is also possible in this situation.

Improper Control of Generation of Code ('Code Injection')

CWE-94

edit-config.pl: This CGI script is used to modify settings in a configuration file.


               
}
# code to add a field/key to a file goes here
# code to set key to a particular file goes here
# code to delete key from a particular file goes here
eval($code);# this is super-efficient code, especially if you have to invoke# any one of dozens of different functions!
handleConfigAction($configfile, param('action'));
print "No action specified!\n";

The script intends to take the 'action' parameter and invoke one of a variety of functions based on the value of that parameter - config_file_add_key(), config_file_set_key(), or config_file_delete_key(). It could set up a conditional to invoke each function separately, but eval() is a powerful way of doing the same thing in fewer lines of code, especially when a large number of functions or variables are involved. Unfortunately, in this case, the attacker can provide other values in the action parameter, such as: add_key(",","); system("/bin/ls"); This would produce the following string in handleConfigAction(): config_file_add_key(",","); system("/bin/ls"); Any arbitrary Perl code could be added after the attacker has "closed off" the construction of the original function call, in order to prevent parsing errors from causing the malicious eval() to fail before the attacker's payload is activated. This particular manipulation would fail after the system() call, because the "_key(\$fname, \$key, \$val)" portion of the string would cause an error, but this is irrelevant to the attack because the payload has already been activated.

Overview

Type

Microsoft Windows

First reported 6 years ago

2018-08-15 17:29:00

Last updated 6 years ago

2018-09-07 15:37:00

Affected Software

Microsoft Windows 10 1703

1703

Microsoft Windows 10 1709

1709

Microsoft Windows 10 1803

1803

Microsoft Windows RT 8.1

Microsoft Windows Server 2008 Service Pack 2

Microsoft Windows Server 2012

Microsoft Windows Server 2016

Microsoft Windows Server 2016 1709

1709

Microsoft Windows Server 2016 1803

1803

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