CVE-2019-14287 - Improper Input Validation

Severity

88%

Complexity

27%

Confidentiality

98%

In Sudo before 1.8.28, an attacker with access to a Runas ALL sudoer account can bypass certain policy blacklists and session PAM modules, and can cause incorrect logging, by invoking sudo with a crafted user ID. For example, this allows bypass of !root configuration, and USER= logging, for a "sudo -u \#$((0xffffffff))" command.

In Sudo before 1.8.28, an attacker with access to a Runas ALL sudoer account can bypass certain policy blacklists and session PAM modules, and can cause incorrect logging, by invoking sudo with a crafted user ID. For example, this allows bypass of !root configuration, and USER= logging, for a "sudo -u \#$((0xffffffff))" command.

CVSS 3.1 Base Score 8.8. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

CVSS 2.0 Base Score 9. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:S/C:C/I:C/A:C).

Demo Examples

Improper Input Validation

CWE-20

This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.


               
...

The user has no control over the price variable, however the code does not prevent a negative value from being specified for quantity. If an attacker were to provide a negative value, then the user would have their account credited instead of debited.

Improper Input Validation

CWE-20

This example asks the user for a height and width of an m X n game board with a maximum dimension of 100 squares.


               
.../* board dimensions */
die("No integer passed: Die evil hacker!\n");
die("No integer passed: Die evil hacker!\n");
die("Value too large: Die evil hacker!\n");

While this code checks to make sure the user cannot specify large, positive integers and consume too much memory, it does not check for negative values supplied by the user. As a result, an attacker can perform a resource consumption (CWE-400) attack against this program by specifying two, large negative values that will not overflow, resulting in a very large memory allocation (CWE-789) and possibly a system crash. Alternatively, an attacker can provide very large negative values which will cause an integer overflow (CWE-190) and unexpected behavior will follow depending on how the values are treated in the remainder of the program.

Improper Input Validation

CWE-20

The following example shows a PHP application in which the programmer attempts to display a user's birthday and homepage.


               
echo "Birthday: $birthday<br>Homepage: <a href=$homepage>click here</a>"

The programmer intended for $birthday to be in a date format and $homepage to be a valid URL. However, since the values are derived from an HTTP request, if an attacker can trick a victim into clicking a crafted URL with <script> tags providing the values for birthday and / or homepage, then the script will run on the client's browser when the web server echoes the content. Notice that even if the programmer were to defend the $birthday variable by restricting input to integers and dashes, it would still be possible for an attacker to provide a string of the form:


               
2009-01-09--

If this data were used in a SQL statement, it would treat the remainder of the statement as a comment. The comment could disable other security-related logic in the statement. In this case, encoding combined with input validation would be a more useful protection mechanism.

Furthermore, an XSS (CWE-79) attack or SQL injection (CWE-89) are just a few of the potential consequences when input validation is not used. Depending on the context of the code, CRLF Injection (CWE-93), Argument Injection (CWE-88), or Command Injection (CWE-77) may also be possible.

Improper Input Validation

CWE-20

This function attempts to extract a pair of numbers from a user-supplied string.


               
}
die("Did not specify integer value. Die evil hacker!\n");
/* proceed assuming n and m are initialized correctly */

This code attempts to extract two integer values out of a formatted, user-supplied input. However, if an attacker were to provide an input of the form:


               
123:

then only the m variable will be initialized. Subsequent use of n may result in the use of an uninitialized variable (CWE-457).

Improper Input Validation

CWE-20

The following example takes a user-supplied value to allocate an array of objects and then operates on the array.


               
}
list[0] = new Widget();
die("Negative value supplied for list size, die evil hacker!");

This example attempts to build a list from a user-specified value, and even checks to ensure a non-negative value is supplied. If, however, a 0 value is provided, the code will build an array of size 0 and then try to store a new Widget in the first location, causing an exception to be thrown.

Improper Input Validation

CWE-20

This application has registered to handle a URL when sent an intent:


               
}......
}
}
int length = URL.length();
...

The application assumes the URL will always be included in the intent. When the URL is not present, the call to getStringExtra() will return null, thus causing a null pointer exception when length() is called.

Overview

First reported 5 years ago

2019-10-17 18:15:00

Last updated 5 years ago

2019-10-23 05:15:00

Affected Software

Fedora 30

30

Fedora 31

31

Debian Linux 8.0 (Jessie)

8.0

Debian Linux 9.0

9.0

Debian Linux 10

10

openSUSE Leap 15.0

15.0

OpenSUSE Leap 15.1

15.1

Canonical Ubuntu Linux 12.04 ESM (Extended Security Maintenance)

12.04

Canonical Ubuntu Linux 14.04 ESM Edition

14.04

Canonical Ubuntu Linux 16.04 LTS (Long-Term Support)

16.04

Canonical Ubuntu Linux 18.04 LTS Edition

18.04

Canonical Ubuntu Linux 19.04

19.04

References

openSUSE-SU-2019:2316

Mailing List, Third Party Advisory

openSUSE-SU-2019:2333

Mailing List, Third Party Advisory

http://packetstormsecurity.com/files/154853/Slackware-Security-Advisory-sudo-Updates.html

Third Party Advisory, VDB Entry

[oss-security] 20191014 Sudo: CVE-2019-14287

Exploit, Mailing List, Third Party Advisory

[oss-security] 20191023 Membership application for linux-distros - VMware

[oss-security] 20191029 Re: Membership application for linux-distros - VMware

RHBA-2019:3248

RHSA-2019:3197

RHSA-2019:3204

RHSA-2019:3205

RHSA-2019:3209

RHSA-2019:3219

RHSA-2019:3278

RHSA-2019:3694

RHSA-2019:3754

RHSA-2019:3755

RHSA-2019:3895

RHSA-2019:3916

RHSA-2019:3941

RHSA-2019:4191

RHSA-2020:0388

[debian-lts-announce] 20191017 [SECURITY] [DLA 1964-1] sudo security update

Mailing List, Third Party Advisory

FEDORA-2019-9cb221f2be

Third Party Advisory

FEDORA-2019-72755db9c7

FEDORA-2019-67998e9f7e

Third Party Advisory

https://resources.whitesourcesoftware.com/blog-whitesource/new-vulnerability-in-sudo-cve-2019-14287

20191015 [slackware-security] sudo (SSA:2019-287-01)

Issue Tracking, Mailing List, Third Party Advisory

20191015 [SECURITY] [DSA 4543-1] sudo security update

Issue Tracking, Mailing List, Third Party Advisory

GLSA-202003-12

https://security.netapp.com/advisory/ntap-20191017-0003/

Third Party Advisory

https://support.f5.com/csp/article/K53746212?utm_source=f5support&amp;utm_medium=RSS

https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbns03976en_us

USN-4154-1

Third Party Advisory

DSA-4543

Third Party Advisory

[oss-security] 20191015 Re: Sudo: CVE-2019-14287

Mailing List, Patch, Third Party Advisory

https://www.sudo.ws/alerts/minus_1_uid.html

Exploit, Vendor Advisory

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