• 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

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

 | 

CrushFTP zero-day actively exploited at least since July 18

 | 

Hardcoded credentials found in HPE Aruba Instant On Wi-Fi devices

 | 

MuddyWater deploys new DCHSpy variants amid Iran-Israel conflict

 | 

U.S. CISA urges to immediately patch Microsoft SharePoint flaw adding it to its Known Exploited Vulnerabilities catalog

 | 

Microsoft issues emergency patches for SharePoint zero-days exploited in "ToolShell" attacks

 | 

SharePoint zero-day CVE-2025-53770 actively exploited in the wild

 | 

Singapore warns China-linked group UNC3886 targets its critical infrastructure

 | 

U.S. CISA adds Fortinet FortiWeb flaw to its Known Exploited Vulnerabilities catalog

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 54

 | 

Security Affairs newsletter Round 533 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

Radiology Associates of Richmond data breach impacts 1.4 million people

 | 

Fortinet FortiWeb flaw CVE-2025-25257 exploited hours after PoC release

 | 

Authorities released free decryptor for Phobos and 8base ransomware

 | 

Anne Arundel Dermatology data breach impacts 1.9 million people

 | 

LameHug: first AI-Powered malware linked to Russia’s APT28

 | 

5 Features Every AI-Powered SOC Platform Needs in 2025

 | 

Broadcom patches critical VMware flaws exploited at Pwn2Own Berlin 2025

 | 
  • 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
  • A Cobalt Strike flaw exposed attackers’ infrastructure

A Cobalt Strike flaw exposed attackers’ infrastructure

Pierluigi Paganini March 03, 2019

According to security experts at Fox-IT, a recently addressed flaw in the Cobalt Strike penetration testing platform could be exploited to identify attacker servers.

Security experts at Fox-IT discovered that a recently addressed vulnerability in the Cobalt Strike penetration testing platform could be exploited to identify attacker servers.

The vulnerability was addressed in Cobalt Strike 3.13, Fox-IT experts argue the flaw was in the platform for almost 7 years, since the platform has been using NanoHTTPD in 2012.

The Cobalt Strike platform was developed for Adversary Simulations and Red Team Operations, but it has also become popular among threat actors over the past years (including APT29 and FIN7).

It is quite easy to find pirated versions of the software that were used by attackers in the wild.

The issue was related to the presence of extraneous whitespace in server responses, it was used security experts to identify Cobalt Strike servers used involved in the attacks.

Cobalt STrike extraneus whitespace

The Java-based platform is composed of two components, the implant (the beacon) and a server (the team server). The server allows to manage the Cobalt Strike beacons and serve the beacon payload, landing pages and other arbitrary files.

Experts pointed out that communication with servers can be fingerprinted via Intrusion Detection System (IDS) signatures and other techniques.

“On top of collaboration, the team server also acts as a webserver where the beacons connect to for Command & Control, but it can also be configured to serve the beacon payload, landing pages and arbitrary files.” reads the advisory published by Fox-IT

“Communication to these servers can be fingerprinted with the use of Intrusion Detection System (IDS) signatures such as Snort, but with enough customization of the beacon, and/or usage of a custom TLS certificate, this becomes troublesome.”

While analyzing the Cobalt Strike team servers, experts discovered the bug in the webserver component (which is based on NanoHTTPD, an open source webserver written in Java). The component returns unexpected whitespace in all its HTTP responses allowing the identification of publicly-exposed NanoHTTPD servers, including Cobalt Strike team server installs used by attackers.

Experts used public scan data, such as Rapid7 Labs Open Data, and the knowledge of how to fingerprint NanoHTTPD servers, to historically identify the state of team servers exposed on the Internet.

“The graphs shows a steady growth of Cobalt Strike (NanoHTTPD) webservers on port 80 and 443 which is a good indication of the increasing popularity of this framework.” continues the analysis published by the experts. “The decline since the start of 2019 is most likely due to the “extraneous space” fix, thus not showing up in the scan data when applying the fingerprint.”

Fox-IT observed 7718 unique Cobalt Strike team server or NanoHTTPD hosts between the period of 2015-01 and 2019-02, it is important to note that some of them are used for legitimate services.

“Organizations are encouraged to use the published list with Cobalt Strike team servers IP addresses to retroactively verify whether they have been targeted with this tooling by either a red team or an adversary in the recent past. The IP addresses can be checked with e.g. firewall and proxy logs, or on aggregate against SIEM data. To minimize the amount of false positives, the reader is urged to take the corresponding first and last seen dates into consideration.” the expert conclude.

“For the ‘red team readers’ of this blog looking for ways to avoid their Cobalt Strike team server being both publicly available and easy to fingerprint, see the Cobalt Strike Team Server Population Study blog for a detailed set of mitigations. Furthermore, Red Teams are encouraged to critically examine their toolsets in use or rely on their Blue Team, for potential tell-tales and determine the appropriate way to apply and mitigate such findings for both Red and Blue team purposes.” Fox-IT concludes.

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

Pierluigi Paganini

(SecurityAffairs – Cobalt Strike, hacking)

[adrotate banner=”5″]

[adrotate banner=”13″]


facebook linkedin twitter

Cobalt Strike Hacking penetration testing Pierluigi Paganini Security Affairs

you might also like

Pierluigi Paganini July 23, 2025
Microsoft linked attacks on SharePoint flaws to China-nexus actors
Read more
Pierluigi Paganini July 22, 2025
Cisco confirms active exploitation of ISE and ISE-PIC flaws
Read more

leave a comment

newsletter

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

    recent articles

    Microsoft linked attacks on SharePoint flaws to China-nexus actors

    APT / July 23, 2025

    Cisco confirms active exploitation of ISE and ISE-PIC flaws

    Hacking / July 22, 2025

    SharePoint under fire: new ToolShell attacks target enterprises

    Hacking / July 22, 2025

    CrushFTP zero-day actively exploited at least since July 18

    Hacking / July 22, 2025

    Hardcoded credentials found in HPE Aruba Instant On Wi-Fi devices

    Security / July 22, 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