A vulnerability was found in Microsoft Internet Explorer 11 (Web Browser). It has been classified as problematic. This affects some unknown processing of the component MHT File Handler. The manipulation with an unknown input leads to a xml external entity reference vulnerability. CWE is classifying the issue as CWE-611. The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output. This is going to have an impact on confidentiality.

The weakness was disclosed 03/27/2019 by John Page as confirmed advisory (Website). The advisory is shared at hyp3rlinx.altervista.org. The public release happened without involvement of Microsoft. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a public exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/29/2020). It is expected to see the exploit prices for this product decreasing in the near future. The advisory points out:

Internet Explorer is vulnerable to XML External Entity attack if a user opens a specially crafted .MHT file locally. This can allow remote attackers to potentially exfiltrate Local files and conduct remote reconnaissance on locally installed Program version information. Example, a request for "c:\Python27\NEWS.txt" can return version information for that program.

A public exploit has been developed by John Page and been published immediately after the advisory. The exploit is shared for download at hyp3rlinx.altervista.org. It is declared as proof-of-concept. We expect the 0-day to have been worth approximately $25k-$100k. The advisory illustrates:

Upon opening the malicious ".MHT" file locally it should launch Internet Explorer. Afterwards, user interactions like duplicate tab "Ctrl+K" and other interactions like right click "Print Preview" or "Print" commands on the web-page may also trigger the XXE vulnerability. However, a simple call to the window.print() Javascript function should do the trick without requiring any user interaction with the webpage. Importantly, if files are downloaded from the web in a compressed archive and opened using certain archive utilities MOTW may not work as advertised. Typically, when instantiating ActiveX Objects like "Microsoft.XMLHTTP" users will get a security warning bar in IE and be prompted to activate blocked content. However, when opening a specially crafted .MHT file using malicious <xml> markup tags the user will get no such active content or security bar warnings.

The problem might be mitigated by replacing the product with as an alternative. The advisory contains the following remark:

MSRC reponse April 10, 2019: "We determined that a fix for this issue will be considered in a future version of this product or service. At this time, we will not be providing ongoing updates of the status of the fix for this issue, and we have closed this case."

Productinfo

Type

• Web Browser

Vendor

• Microsoft

Name

• Internet Explorer

Version

• 11

License

• commercial

Support

• end of life

CPE 2.3info

• 🔍

CPE 2.2info

• 🔍

Video

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Exploitinginfo

Threat Intelligenceinfo

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Entryinfo

Submitinfo

Accepted

• Submit #59: Microsoft Internet Explorer v11 XML External Entity Injection 0day (by hyp3rlinx)

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