• 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

Allianz Life data breach exposed the data of most of its 1.4M customers

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55

 | 

Security Affairs newsletter Round 534 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

Law enforcement operations seized BlackSuit ransomware gang’s darknet sites

 | 

Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

 | 

Operation CargoTalon targets Russia’s aerospace with EAGLET malware,

 | 

Unpatched flaw in EoL LG LNV5110R cameras lets hackers gain Admin access

 | 

Koske, a new AI-Generated Linux malware appears in the threat landscape

 | 

Mitel patches critical MiVoice MX-ONE Auth bypass flaw

 | 

Coyote malware is first-ever malware abusing Windows UI Automation

 | 

SonicWall fixed critical flaw in SMA 100 devices exploited in Overstep malware attacks

 | 

DSPM & AI Are Booming: $17.87B and $4.8T Markets by 2033

 | 

Stealth backdoor found in WordPress mu-Plugins folder

 | 

U.S. CISA adds CrushFTP, Google Chromium, and SysAid flaws to its Known Exploited Vulnerabilities catalog

 | 

U.S. CISA urges FCEB agencies to fix two Microsoft SharePoint flaws immediately and added them to its Known Exploited Vulnerabilities catalog

 | 

Sophos fixed two critical Sophos Firewall vulnerabilities

 | 

French Authorities confirm XSS.is admin arrested in Ukraine

 | 

Microsoft linked attacks on SharePoint flaws to China-nexus actors

 | 

Cisco confirms active exploitation of ISE and ISE-PIC flaws

 | 

SharePoint under fire: new ToolShell attacks target enterprises

 | 
  • 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
  • Malware
  • Sefnit botnet-Microsoft has silently uprooted Tor Browser from more than 2 Million PC

Sefnit botnet-Microsoft has silently uprooted Tor Browser from more than 2 Million PC

Pierluigi Paganini January 22, 2014

Microsoft has uprooted Tor Browser from more than 2 Million Systems to eradicate Sefnit botnet. It has done it silently without user agreement.

It was August 2013 when security experts noted a spike in Tor traffic network caused by cybercriminals activities, the malware specialists discovered a botnet based on Mevade malware, in mid-August the number of Tor users had skyrocketed from 500,000 to close to 3 million. The security expert speculated that traffic was generated by communication of bots with C&C servers hidden in the Tor network. Bot agent for the Mevade malware family used “Sefnit” code dated 2009 that included Tor connectivity. The malware implemented a backup mechanism for its C&C communications with a Tor component.

“The botnet of Sefnit hosted proxies are used to relay HTTP traffic to pretend to click on advertisements,” said Microsoft Malware Protection Center researcher Geoff McDonald.

The botnet was infecting millions of computers for click fraud and bitcoin mining, so in October 2013, Microsoft decided decided to go on the attack with a stealth offensive to decapitate the Tot-botnet based on the Sefnit malware, an agent belonging to the same click-fraud scam family malicious code of Mevade  .

Microsoft decided to silently remotely remove older versions Tor Browser software from nearly 2 Million systems, the operation was conducted without informing both Microsoft customers neither the Tor developers.

Sefnit caused Tor traffic spike

Microsoft experts remarked that Sefnit malware silently installed a Tor client on infected machines, even if it  is removed the Tor service will be left and still regularly connect to the Tor Network. The Sefnit removal according Microsoft requests the execution of a specific procedures hard to explain to its customers, that’s why Microsoft decided to remotely erase every component belonging to the botnet.

“’The security problem lies in the fact that during a Sefnit component infection, the Tor client service is also silently installed in the background. Even after Sefnit is removed, unless specific care is taken, the Tor service will be left and still regularly connect to the Tor Network.‘” States the official blog post.

Sefnit caused Tor traffic spike TIMELINE

To sanitize the infected machines, Microsoft has updated all its security products including information and instructions to detect the presence of malicious Tor client service and remove it.

“We modified our signatures to remove the Sefnit-added Tor client service. Signature and remediation are included in all Microsoft security software, including Microsoft Security Essentials, Windows Defender on Windows 8, Microsoft Safety Scanner, Microsoft System Center Endpoint Protection, and Windows Defender Offline.” Reports Microsoft.

Microsoft points out several vulnerabilities in the Tor version v0.2.3.25  used by Sefnit, unfortunately the bundle is not upgradeable to the successive version, so the company decided to close loophole uninstalling the browser instead to simply delete the Sefnit code.

“Tor is a good application used to anonymize traffic and usually poses no threat. Unfortunately, the version installed by Sefnit is v0.2.3.25 – and does not self-update. The latest Tor release builds at the time of writing is v0.2.4.20.“

Sefnit caused Tor browser flaws

The side effect was that the decision of Microsoft impacted also all the Tor users that intentionally have installed the anonymizing browser, 2 Million systems were cleaned with this technique.

It is very concerning the fact that the company could arbitrary decide to remove a software on any system based on its OS.

The Internet community has considered the decision of Microsoft to remove Tor browsers without any alert, too arrogant. Many experts are questioning about why Microsoft has not followed the same policy for its IE browser which is known to be suffering from hundreds of vulnerabilities, many of which are critical and which expose the safety of customers at serious risk.

Pierluigi Paganini

(Security Affairs –  Microsoft, Sefnit)


facebook linkedin twitter

banking trojan botnet Cybercrime i2Ninja Kaspersky Lab Mevade Sefnit Skynet Tor network Tor-based malware

you might also like

Pierluigi Paganini July 27, 2025
SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55
Read more
Pierluigi Paganini July 26, 2025
Law enforcement operations seized BlackSuit ransomware gang’s darknet sites
Read more

leave a comment

newsletter

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

    recent articles

    Allianz Life data breach exposed the data of most of its 1.4M customers

    Data Breach / July 27, 2025

    SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55

    Malware / July 27, 2025

    Security Affairs newsletter Round 534 by Pierluigi Paganini – INTERNATIONAL EDITION

    Breaking News / July 27, 2025

    Law enforcement operations seized BlackSuit ransomware gang’s darknet sites

    Cyber Crime / July 26, 2025

    Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

    Intelligence / July 26, 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