Client-side remote file upload & command execution

SEC Consult Vulnerability Lab Security Advisory < 20111012-0 >


title: Client-side remote file upload & command execution

product: Microsoft Forefront Unified Access Gateway Remote

Access Agent (signed Java applet)

vulnerable version:

fixed version:

CVE number: CVE-2011-1969

impact: critical


found: 2011-04-20

by: Elisabeth Demeter / SEC Consult Vulnerability Lab



Vendor description:


"Forefront Unified Access Gateway 2010 (UAG) delivers comprehensive, secure

remote access to corporate resources for employees, partners, and vendors on

both managed and unmanaged PCs and mobile devices. Utilizing a combination of

connectivity options, ranging from SSL VPN to Direct Access, as well as built

in configurations and policies, Forefront UAG provides centralized and easy

management of your organization's complete anywhere access offering.


Integrating a deep understanding of the applications published, the state of

health of the devices being used to gain access, and the user's identity –

Forefront UAG enforces granular access controls and policies to deliver

comprehensive remote access, ensure security, and reduce management costs

and complexity."



Vulnerability overview/description:


The client-side endpoint security solution (Microsoft Forefront UAG), e.g.

supplied by Microsoft Outlook Web App, uses either a signed Java applet

(Remote Access Agent) or an ActiveX Control (Endpoint Components) to connect

to a VPN and perform local compliance scans on the client.


Due to quality issues within the software, an attacker is able to access

insecure methods from the "trustworthy" Java applet and exploit those features

to compromise all client systems that trust the correctly signed Java applet

(e.g. all users that need to use this software for accessing internal systems

over company VPN).


The ActiveX control has the same functionality, which is why it is strongly

presumed that a similar attack is possible.



Microsoft UAG Remote Access Agent contains the MicrosoftClient.jar which in

turn contains This class creates an "Agent" object

that writes one of the following three files to the client system (depending

on the operating system):

* agent_win_helper.jar

* agent_mac_helper.jar

* agent_lin_helper.jar


It is only checked if the jar is signed, but not who signed it, so any created

self-signed jar that is named like one of these files can be used. The

manipulated jar files can only be loaded if the codebase is completely on the

attacker system (the MicrosoftClient.jar and all the other needed files need

to be on the attacker system).


The agent_xxx_helper.jar needs to include any executable with the name

"ProxyProcess_Win.exe" and/or "AttachmentWiper.exe" which is executed during

the doInit() function which in turn is called during the init() function of




Summing up, an attacker is able to upload arbitrary executable files to remote

clients and then immediately execute them without notice as a signed Java

applet is being used (if "Always trust content from this publisher" has been

checked - otherwise an unsuspicious Java digital signature verification popup

will occur).


Possible attack vectors are drive-by downloads just by visiting malicious

websites but also through emails, any XSS on unsuspicous websites, etc.


Proof of concept:


The exploit will not be published, but a video demonstrating this issue has

been created. It can be found at the following URL:



Vulnerable / tested versions:


The Forefront UAG Remote Access Agent has been tested and successfully



Vulnerable signed Java applet certificate SHA1 fingerprint:



According to Microsoft, the following systems are vulnerable:

- Microsoft Forefront Unified Access Gateway 2010

- Microsoft Forefront Unified Access Gateway 2010 Update 1

- Microsoft Forefront Unified Access Gateway 2010 Update 2

- Microsoft Forefront Unified Access Gateway 2010 Service Pack 1



Vendor contact timeline:


2011-04-22: Contacted vendor through

2011-04-22: Vendor: Very fast response, issue is being investigated:

MSRC case 11257

2011-04-28: Contacted vendor asking for updates

2011-05-17: Contacted vendor again asking for updates

2011-05-19: Contacted personal contact at MSRC asking for updates

2011-05-19: Answer from personal contact and from case manager: they could reproduce

the issue and are currently working on a fix timeline, fix expected in

the next few months

2011-05-30: Contacted vendor informing about our publishing schedule: minimal

information will be published on June 13th, mutual customers will be

informed in more detail, advisory and video will be published when issue

is fixed

2011-05-31: Answer from vendor to postpone the publishing date

2011-06-06: Proposal to the vendor to postpone the publishing date to July 12th

2011-06-06: Answer from vendor ok-ing it

2011-06-22: Update from vendor to postpone the publishing date again

2011-06-23: Update from vendor with more information about the fixing schedule

2011-06-28: Contacted vendor accepting a possible postponing of the July 12th

publishing date, also offering dates for a phone-conference call

2011-06-28: Answer from vendor about dates for phone-conference call

2011-06-29: New offering of dates for phone-conference call

2011-07-13: Conference call

2011-08-21: Contacted vendor about updates

2011-08-22: Update from third party will be in october, so patch from vendor will also be in october

2011-09-26: Contacted vendor about specific publishing dates

2011-09-26: Publishing dates confirmed by vendor for October 11th


We thank the people from Microsoft for their cooperation!






Update your Microsoft Forefront UAG.





Deactivate Java in your browser. Login to Microsoft Outlook Web App should

still be possible.


Add the entry for the following file:



# UAG Client MicrosoftClient.jar

SHA1-Digest-Manifest: dBKbNW1PZSjJ0lGcCeewcCrYx5g=


Remove the affected trusted certificate (see fingerprint above) of Microsoft

Corporation from the Java control panel (jcontrol) from all clients.


Don't fully trust signed Java applets (in general).


This workaround can be applied to MAC, Linux, and Windows systems by

modifying the appropriate blacklist file on each system.


If the VPN functionality (or any other) is absolutely needed, only "trust"

it on the company site (don't store the certificate forever and verify each

connect) and don't click on it when the Java certificate popup occurs on other

web pages.




Advisory URL:




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Mail: research at sec-consult dot com


EOF E. Demeter / 2011