Twenty Year Anniversary

Windows Attachment Manager Incorrect High Risk JAR Handling

Windows Attachment Manager Incorrect High Risk JAR Handling
Posted Oct 27, 2017
Authored by Stevie Lamb

The Windows Attachment Manager does not correctly handle JAR files marked as high risk when accessed via Internet Explorer 11.

tags | advisory
systems | windows
MD5 | 0a2b101ba0ba57f6c9393f4be248261b

Windows Attachment Manager Incorrect High Risk JAR Handling

Change Mirror Download
Scenario:

The Windows Attachment Manager does not correctly handle JAR files marked as
"high risk" when accessed via Internet Explorer 11.

This leads to direct execution of any JAR file when a user clicks "Open"
rather than "Save" or "Save as", when the expected behaviour would be a nag
dialog.



Other files added to the same "high risk" category behave as expected,
regardless of whether they are directly launched or first saved.

Currently neither Chrome, Edge nor Firefox browsers provide an "Open" option
for such files, and so are unaffected.



With some social engineering this behaviour may be exploited to gain code
execution at the privilege level of the affected user.

This is most likely to be successful when the user has been conditioned to
expect warnings from the Attachment Manager about potentially unsafe files.



MS Security decided this wasn't a security issue and by their published
definitions I accept that assertion.

But sharing's caring, this issue can and therefore probably will be abused,
if it hasn't already.



To reproduce:



Client OS : Windows 10 Pro (version 10.0.14393)

Browser : IE11 (version 11.00.14393.0) *supplied with OS for backwards
compatibility



Sample Attachment Manager configuration


Setting

State

Attribute : Value


Trust logic for file attachments

Enabled

Determine risk by : Preferring the file handler


Default risk level for file attachments

Enabled

Set the default risk level : High risk


Inclusion list for high-risk file types

Enabled

.com;.bat;.exe;.pif;.scr;.msi;.ps1;.jar;.sh;.py;.Zip;.Rar;.7z;.gz;.tar;.vbs;
.js;.wsf


Inclusion list for low file types

Enabled



Inclusion list for moderate risk file types

Enabled

.doc;.xlsx;.docx;



1. Download any JAR file using the built-in IE11 (x64 or x86) and opt
to open it.

2. The file opens without any nag dialog indicating the file type is
potentially harmful.



Hope it's useful.

Kind regards,
Stevie

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

December 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Dec 1st
    11 Files
  • 2
    Dec 2nd
    1 Files
  • 3
    Dec 3rd
    18 Files
  • 4
    Dec 4th
    40 Files
  • 5
    Dec 5th
    16 Files
  • 6
    Dec 6th
    50 Files
  • 7
    Dec 7th
    12 Files
  • 8
    Dec 8th
    1 Files
  • 9
    Dec 9th
    1 Files
  • 10
    Dec 10th
    15 Files
  • 11
    Dec 11th
    20 Files
  • 12
    Dec 12th
    0 Files
  • 13
    Dec 13th
    0 Files
  • 14
    Dec 14th
    0 Files
  • 15
    Dec 15th
    0 Files
  • 16
    Dec 16th
    0 Files
  • 17
    Dec 17th
    0 Files
  • 18
    Dec 18th
    0 Files
  • 19
    Dec 19th
    0 Files
  • 20
    Dec 20th
    0 Files
  • 21
    Dec 21st
    0 Files
  • 22
    Dec 22nd
    0 Files
  • 23
    Dec 23rd
    0 Files
  • 24
    Dec 24th
    0 Files
  • 25
    Dec 25th
    0 Files
  • 26
    Dec 26th
    0 Files
  • 27
    Dec 27th
    0 Files
  • 28
    Dec 28th
    0 Files
  • 29
    Dec 29th
    0 Files
  • 30
    Dec 30th
    0 Files
  • 31
    Dec 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close