Tag Archives: Routers

CallStranger UPnP Vulnerability

Earlier this month an independent security researcher responsibly disclosed the CallStranger UPnP (defined) vulnerability.

Why is the CallStranger vulnerability and why is it important?
This vulnerability primarily impacts internet service providers, device vendors and enterprises. If an attacker were to exploit the vulnerability it could be used to:

  1. Send network traffic to destinations of the threat actor’s choice
  2. Create amplified DDoS (defined) attacks
  3. To carry out data exfiltration (by bypassing data loss prevention security measures) making this type of activity harder to detect.
  4. Carry out port scanning of exposed UPnP devices on the same network looking for further meaning of exploitation

There are billions of potentially vulnerable devices in use across the world. Such devices include home routers, broadband modems, smart TVs, printers, cameras, media gateways, Windows based devices and game consoles. A list of known vulnerable devices is available on the website dedicated to this vulnerability but it cannot be a complete list due to the large number of device vendors and device models impacted.

How can a threat actor exploit this vulnerability?
The threat actor would need to send a specially crafted HTTP SUBSCRIBE request to a vulnerable device. If a vulnerable UPnP is exposed to the public internet, it can be located by the threat actor for example using the Shodan tool (defined). This server side request forgery (SSRF)(defined) is not trivial to exploit.

What can an organisation or an individual do to be protected against this vulnerability?
As stated above, this vulnerability primarily impacts internet service providers, device vendors and enterprises. Please see the section titled “AM I VULNERABLE & WHAT TO DO?” of the website dedicated to this vulnerable for the necessary steps you should take.

Enterprises, businesses and ISPs can find an appropriate IDS signature for detecting the exploitation of this vulnerability from this CERT page.

Consumers/home users can also find the appropriate steps in that named section of the dedicated website.

Thank you.

March 2020 Update Summary

Update: 28th March 2020
I have added the details of the security updates released by Apple on the 24th March near the end of this post. Thank you.

Update: 25th March 2020
Adobe has released a further update for Creative Cloud Desktop. I have added the details below to the Adobe updates list.

VMware have also released VMware Fusion 11.5.3 to more completely address a previously patched vulnerability. Details are below in the VMware updates list.

Thank you.

Update: 23rd March 2020

Since originally writing this post, Adobe published their security updates a week later than usual. Further details are listed below.

Thank you.

Adobe Acrobat and Reader: 13x Priority 2 CVEs (defined)resolved (9x Critical and 4x Important severity)
Adobe Bridge: 2x Priority 3 CVEs resolved (2x Critical severity)
Adobe ColdFusion:  2x Priority 2 CVEs resolved (2x Critical severity)
Adobe Creative Cloud Desktop: 1x Priority 2 CVE resolved (1x Critical severity)
Adobe Experience Manager: 1x Priority 2 CVE resolved (1x Important severity)
Adobe Genuine Integrity Service: 1x Priority 3 CVE resolved (1x Important severity)
Adobe Photoshop: 21x Priority 3 CVEs resolved (15x Critical and 6x Important severity)

Update: 15th March 2020:
Security researcher Kevin Beaumont has provided further details of the critical SMBv3.1 vulnerability affecting Windows 10 Version 1903 and 1909. In summary the vulnerability is not trivial to exploit and the number of systems at the time of writing (13th March) vulnerability to the exploit had already dropped by 25%.

Update: 12th March 2020:
Microsoft have released an update to resolve the SMBv3 vulnerability now designated CVE-2020-0796, (EternalDarkness or SMBGhost) please apply it to any Windows 10 Server or Windows 10 workstation system running Windows 10 Version 1903 or 1909 as soon as possible. Please also make certain that such systems are not exposing port 445 to the internet (please seethe FAQ in their information on the relevant update).

An internet scan by security researchers of vulnerable estimates that there are 48,000 vulnerable Windows 10 systems. You can use the ollypwn scan (created by a Danish security researcher) can be used to check if a system is vulnerable.

I wish to add the following useful clarification (which was written before the Microsoft security update became available) from Richard Melick, senior technical product manager at Automox in relation to this SMBv3 vulnerability:

“Considering that SMBv3 is not as widely used as SMBv1, the potential immediate impact of this threat is most likely lower than past vulnerabilities. But that does not mean organizations should be disregarding any endpoint hardening that can happen now while Microsoft works on a patch…it’s better to respond today and disable SMBv3 and block TCP port 445. Respond now and vulnerabilities end today”.

To all of my readers, please stay safe during these challenging times. Thank you.

Update: 11th March 2020
As expected, yesterday Microsoft  released their scheduled updates to resolve 115 CVEs (defined). Unusually for this month, Adobe has not released any updates.

Microsoft’s monthly summary; lists Known Issues for 14 Microsoft products but all have workarounds or resolution steps listed just as the previous month’s did.

A further useful source of update related information is the US Computer Emergency Readiness Team (CERT) (please see the “Information on Security Updates” heading of the “Protecting Your PC” page):


As always for this month’s Microsoft updates, I will prioritize the order of installation below:
For Windows or Windows Server system (Version 1903 and 1909) systems that uses SMBv3, please follow Microsoft’s guidance in the following security advisory while an update is not yet available. Please apply the update as soon as it is made available:

ADV200005 | Microsoft Guidance for Disabling SMBv3 Compression

Please also make certain that TCP port 445 is blocked at the enterprise perimeter firewall to prevent exploitation.

This vulnerability is “wormable” meaning that similar to the WannaCry malware and the BlueKeep vulnerability if exploited it may lead to a very large malware outbreak in a very short time.


Windows LNK: CVE-2020-0684
Windows Media Foundation: CVE-2020-0801 , CVE-2020-0807 , CVE-2020-0809,  CVE-2020-0869
Microsoft Internet Explorer: CVE-2020-0824
Microsoft Browsers: CVE-2020-0768

Microsoft Scripting Engine: CVE-2020-0830 , CVE-2020-0847, CVE-2020-0833 , CVE-2020-0832, CVE-2020-0829 , CVE-2020-0813 , CVE-2020-0826, CVE-2020-0827 , CVE-2020-0825 , CVE-2020-0831, CVE-2020-0811, CVE-2020-0828, CVE-2020-0848, CVE-2020-0823, CVE-2020-0812

Microsoft GDI+: CVE-2020-0881, CVE-2020-0883
Microsoft Word: CVE-2020-0852
Microsoft Dynamics: CVE-2020-0905
Microsoft Edge: CVE-2020-0816


Please install the remaining updates at your earliest convenience.

As per standard best practice; I would recommend backing up the data on any device for which you are installing updates to prevent data loss in the rare event that any update causes unexpected issues.

I have also provided further details of updates available for other commonly used applications and devices below.

To all of my readers, please stay safe during these challenging times. Thank you.

On the 3rd of March, Netgear released 25 security advisories for its modem-router gateways, approximately 40 routers and a range extender. The vulnerability range up to critical in severity.

If you own a Netgear router, range extender or modem-router gateway, please use the guidance within this article (many thanks to Tom’s Guide for this advice and the appropriate how to check for updates steps) to locate your Netgear device model e.g. R6400 and to match it against the available security bulletins to check if your device requires a firmware (defined) update sometimes called a software update. Please install the update if one is available. The above linked to article also describes the varied methods to update your Netgear device.

Intel Security Advisories
Intel have released a series of security advisories this month. The advisories are prioritised below. If you use any of these products, software or devices, please update them as soon as possible especially in the case of the high severity advisories.

Intel Smart Sound Technology Advisory
BlueZ Advisory
Intel NUC Firmware Advisory

Intel MAX 10 FPGA Advisory
Intel Processors Load Value Injection Advisory
Snoop Assisted L1D Sampling Advisory
Intel Optane DC Persistent Memory Module Management Software Advisory
Intel FPGA Programmable Acceleration Card N3000 Advisory
Intel Graphics Drivers Advisory

Mozilla Firefox
Yesterday, Mozilla released Firefox 74 and Firefox ESR (Extended Support Release) 68.6 to resolve the following vulnerabilities:

Firefox 74.0: Addresses 6x high severity CVEs, 6x medium severity CVEs and 1x low CVE

Firefox 68.6 ESR: Addresses 5x high severity CVEs and 3x medium severity CVEs

Firefox 74 also removes support TLS 1.0 (what is TLS, defined) and 1.1 as per Mozilla’s previous timelime, adds a Facebook Container add-in to limit how much the social tracks you across other sites and blocks the ability for other applications to install Firefox add-ons without your knowledge or consent. Further details of these features and other features added can be found within this article (my thanks to Lawrence Abrams of Bleepingcomputer.com for this information).

Google Chrome
Early last week, Google released Chrome version 80.0.3987.132 for Linux, Mac and Windows to resolve 4 security vulnerabilities with the most severe being of high severity.

Google Chrome updates automatically and will apply the update the next time Chrome is closed and then re-opened. Chrome can also be updated immediately by clicking the Options button (it looks like 3 vertically stacked dots) in the upper right corner of the window and choosing “About Google Chrome” from the menu. Follow the prompt to Re-launch Chrome for the updates to take effect.

Apple Security Updates:
On the 24th of March Apple made available the following updates. Notable fixes affect the kernels of macOS, iOS and iPadOS, WebKit (the renderer of Safari), Bluetooth and Safari.

These updates bring Safari to version 13.1 and add updates to its Intelligence Tracking Prevention (ITP) privacy feature while also introducing a block on all 3rd party cookies (defined) by default.

Further details for these updates are as follows:
Apple iOS v13.4 and iPadOS 13.4 (resolves 35x CVEs (defined))
Apple tvOS 13.4: Resolves 20x CVEs.
Apple watchOS 6.2: Resolves 17x CVEs
Apple watchOS 5.3.6 (no CVEs resolved)
Apple iTunes version 12.10.5 for Windows: Resolves 13x CVEs
macOS Catalina 10.15.4, Security Update 2020-002 Mojave, Security Update 2020-002 High Sierra: Resolves 27x CVEs.
Safari 13.1: Resolves 11 CVEs
Apple iCloud for Windows 10.9.3: Resolves 13 CVEs
Apple iCloud for Windows 7.18: Resolves 13 CVEs
Xcode 11.4: Resolves 1 CVE (?: Apple’s post provides little details)


Please see these links from Apple for advice on backing up your iPhone and iPad. Advice for updating tvOS is available here while the steps for updating the Apple Watch are available here.

As always; further details of these updates are available on Apple’s dedicated security updates page.

For advice on how to install updates for Apple devices, please see the steps detailed at the end of this Sophos blog post as well as this link (from my “Protecting Your PC” page).

On the 17th March the OpenSSL Foundation issued OpenSSL 1.1.1e (download/installation links included) which includes a low severity security fix.

FTP mirrors to obtain the necessary downloads are available from here.

Downloadable Tarballs (compressed/packaged code made for distribution) are available from here.

It should also be possible to use the package manager of a Linux/Unix operating system to update your OpenSSL installation as mentioned within the section titled “Installing updates for Linux distributions” on the “Protecting Your PC” page of this blog.

VMware have so far released 2 security advisories this month to resolve vulnerabilities within the following products:

Advisory 1: Severity: Critical:
VMware Workstation Pro / Player (Workstation)
VMware Fusion Pro / Fusion (Fusion)
VMware Horizon Client for Windows
VMware Remote Console for Windows (VMRC for Windows)
Advisory 2: Severity: Important:
VMware Workstation Pro / Player (Workstation)
VMware Fusion Pro / Fusion (Fusion)
VMware Remote Console for Mac (VMRC for Mac)
VMware Horizon Client for Mac
VMware Horizon Client for Windows

Advisory 2 (above) has been updated by VMware to state VMware Fusion has been updated to version 11.5.3 to more comprehensively resolve the vulnerability designated CVE-2020-3950. Please make certain if you use VMwre Fusion that it is the latest version available.

If you use any of the above products, please review the above advisories and install the applicable security updates as soon as possible.

Cable Modems Vulnerable to Cable Haunt Vulnerabilities

If you are cautious with the links you click and when processing your email, you will likely not be vulnerable to these flaws. If you use a cable modem for your internet connection, you should check if your modem is vulnerable and follow the step “What should I do” mentioned below.

In mid-January it was discovered the firmware (defined) of many internet service provider (ISP) modems (specifically combined modems and routers in the same device) was vulnerable to remote takeover by attackers. These vulnerabilities have been named Cable Haunt as an easier to remember reference.

How widespread are the affected modems?
At the least the following manufacturers are affected with up to 200 million vulnerable modems mainly based in Europe but other regions e.g. North America are also affected. Please see also the FAQ “Am I Affected” on the Cable Haunt website.


Other brands of modems confirmed by the wider community as being vulnerable are:

Cisco EPC3928AD
Cisco/Technicolor DPC3216
Humax HGB10R-02
SMC Electronics SMC D3-CCR-v2
Zoom 5370
Virgin Media’s Super Hub 3 and 4 do not appear to be vulnerable.

How serious are these vulnerabilities?
While the vulnerabilities are serious in their impact, namely complete remote compromise of the device, how an attacker could exploit the vulnerabilities to achieve that outcome is not trivial. As per the researchers:

“This could be exploited by an attacker if you visit a malicious website or if they embed the code, for instance in an advert, on a trusted website. It is important to point out that this is not the only attack vector that can be employed, vulnerable mail-clients, exploited IoT devices, public networks etc. are also viable attack vectors”.

Summary of the Technical Aspects of these vulnerabilities
The vulnerability designated formally as CVE-2019-19494 is a buffer overflow (defined) that if exploited could allow remote code execution (defined: the ability for an attacker to remotely carry out any action of their choice on your device) with kernel level (defined) privileges by using JavaScript (defined) within your web browser. The buffer overflow can be exploited using (according to the researchers: “a carefully crafted message the modem can be manipulated to execute arbitrary code specified by a remote attacker”.

An important aspect of the above described exploit is that while the attack is a remote attack (using a victim’s web browser) it results in the local compromise of the modems spectrum analyser. Linked to this; a DNS re-bind attack (defined) can be used to enable an attacker the ability to access the compromised spectrum analyser. The result of the above exploits provides the attackers with (according to the researchers): “full remote control over the entire unit, and all the traffic that flows through it, while being invisible for both the user and ISP,”. This capability could be used to:

  1. Intercept private messages
  2. Redirect traffic
  3. Add the modems to botnets
  4. Replace the devices firmware
  5. Instruct the device to ignore remote system updates (which could be used to patch the vulnerabilities, complicating the resolution of a compromised device by its legitimate owner/user)

How can I protect my organisation or myself from these vulnerabilities?\
For in-depth answers from the researchers to answer this question in the context of an internet service provider (ISP), the user of the modem (e.g. within a small business), as an individual or a security researcher, please see the question “What Should I do” on the dedicated Cable Haunt website:


According to Graham Cluley: “Some ISPs in Scandinavia appear to have remotely patched the cable modems of their customers, but others have some catching up to do it seems.
If your cable modem contains a Broadcom chipset you might want to contact your ISP and ask them what they’re doing about this”.

Thank you.


My sincere thanks to the Cable Haunt researchers Alexander Dalsgaard Krog (Lyrebirds), Jens Hegner Stærmose (Lyrebirds), Kasper Kohsel Terndrup (Lyrebirds) and Simon Vandel Sillesen (Independent) as well as Graham Cluley for the excellent information which this blog post is built upon.

No Fix Planned for Linksys Router Information Disclosure

Earlier this week a security researcher disclosed a vulnerability within Linksys routers that was thought to have been patched back in 2014.

TL DR: No fix for this vulnerability exists. It is made worse if your router is using the default password. With no fix from Linksys expected you may consider using OpenWrt firmware.

Why should this vulnerability be considered important?
This vulnerability is trivial to exploit and can be carried out remotely by an un-skilled attacker. A list of affected Linksys routers is available in Mursch’s report At the time of writing, Linksys have deemed the vulnerability “Not applicable / Won’t fix” following responsible disclosure by Mursch. This information disclosure vulnerability leaks (among other details):

  • MAC address (defined) of every device that’s ever connected to it (full historical record, not just active devices)
  • Device name (such as “TROY-PC” or “Mat’s MacBook Pro”)
  • Operating system (such as “Windows 7” or “Android”)
  • WAN settings
  • Firewall status
  • Firmware update settings
  • DDNS settings

A further example of the information disclosed is present in Mursch’s report. One of the more important elements disclosed is the MAC address. This unique “fingerprint” allows the tracking of a device as it moves across networks and allowing it’s geolocation using a service such as Wigle (we have mentioned Wigle before on this blog). Using this location data, an attacker could plan and conduct targeted attacks against your business/home.

As mentioned above; this vulnerability is made more severe if your Linksys router is using a default password; the following actions can be taken by an attacker (list courtesy of Mr. Troy Mursch):

  • Obtain the SSID and Wi-Fi password in plaintext
  • Change the DNS settings to use a rogue DNS server to hijack web traffic
  • Open ports in the router’s firewall to directly target devices behind the routers (example: 3389/TCP for Windows RDP)
  • Use UPnP to redirect outgoing traffic to the threat actors’ device
  • Create an OpenVPN account (supported models) to route malicious traffic through the router
  • Disable the router’s internet connection or modify other settings in a destructive manner

How can I protect my organisation/myself from this vulnerability?
If your router is one of the vulnerable models listed in Mursch’s report; please make certain the option for automatic firmware updates is enabled (if it is present). Should Linksys correct this vulnerability in the future, you will receive the fix automatically.

Please make certain your Linksys router is not using the default password it is supplied with. With no fix from Linksys expected you may consider using OpenWrt firmware.

Thank you.

MikroTik Routers Exploited to Generate Cryptocurrency

In early August security researchers discovered a large malware campaign under way taking advantage of a now patched vulnerability within MikroTik routers.

Why should this threat be considered important?
This attack is underway since while a patch for an exploit for the Winbox component of the RouterOS being open was patched in one day (on the 23rd of April); there are many users who have not installed this update. The number is estimated to be in the hundreds of thousands including internet service provider (ISP) routers). Once exploited the vulnerability allows an attacker to gain remote administrative (high privilege) access to an affected router. Initially this attack originated in Brazil but has since been extended to over 200k devices worldwide (with a second attack). It’s unclear if its by the same perpetrator as the first attack.

Proof of concept (defined) code made available on GitHub has been modified by unknown attackers to add to all traffic passing through a vulnerable MikroTik router a copy of the Coinhive library along with the relevant Coinhive key to benefit a single attacker by means of cryptocurrency mining (an excellent introduction article to BitCoin and cryptocurrency). This attack isn’t just affecting MikroTik routers; Simon Kenin from Trustwave’s SpiderLabs division found that traffic going to and from a MikroTik router was affected e.g. if a website was hosted behind an affected router it would also be impacted.

More recently the attacker has altered his/her approach to adding the Coinhive script to the error pages of the routers rather than the more noticeable approach described above. That altered approach affects more than 170k routers. These error pages can potentially be accessed millions of time per day earning the attacker funds for each page served. With approximately 1.7 million of these routers online around the world there is the potential for this to get worse.

How can I protect myself from this vulnerability?
If you own/administer a MikroTik router or know someone who does, please ensure that any such devices are using the most recent firmware available from this link. Further advice after upgrading the firmware is also provided by MikroTik at the above link.

Thank you.

VPNFilter: Overview and removal

Update: 24th October 2018:
Researchers from Cisco’s Talos team have discovered further capabilities of this malware. As detailed below the 3rd stage of the malware features:

Provides plugins for the RAT (defined below in the original post) to extend its functionality.

However, the team was able to determine the following extra capabilities:

  1. Packet sniffing (obtain information from passing data packets (defined) on a network connection)
  2. JavaScript (defined) injection used to deliver exploit (a small piece of software used to trigger a known vulnerability to the advantage of an attacker) to a compromised device (most likely a router).
  3. Encrypted tunnelling (defined) to hide data the malware steals as well as the existing command and control data traffic.
  4. Creating network maps (defined)
  5. Remote connection/administration via SSH (Secure Shell)(defined)
  6. Port forwarding (defined)
  7. Create SOCK5 (defined) proxies (defined)
  8. DDoS (defined)

The good news about this malware is that from the Talos team’s research it does not appear that any malware samples remain active. However; they caution it is not possible to assume that this malware has finished its malicious actions and the possibility of its return remains.

Thank you.

Update: 20th June 2018:
If you would prefer a video or a podcast of how to remove this malware from your router, this Sophos blog post provides links to both. The video is hosted on Facebook but a Facebook account isn’t required to view it. Sophos also provide an archive of previous videos on the same Facebook page.

Thank you.

Update: 6th June 2018:
The Cisco Talos team have provided an updated list of known affected routers. I have added these to the list below with “(new)” indicating a new device on the existing list. I have also updated the malware removal advice to provide easier to follow steps.

Thank you.

Original Post:
In late May; a strain of malware known as VPNFilter affecting routers from the vendors listed below was publicly disclosed by the Cisco Talos team:

Affected vendors:
Asus RT-AC66U (new)
Asus RT-N10 (new)
Asus RT-N10E (new)
Asus RT-N10U (new)
Asus RT-N56U (new)
Asus RT-N66U (new)
D-Link DES-1210-08P (new)
D-Link DIR-300 (new)
D-Link DIR-300A (new)
D-Link DSR-250N (new)
D-Link DSR-500N (new)
D-Link DSR-1000 (new)
D-Link DSR-1000N (new)
Huawei HG8245 (new)
Linksys E1200
Linksys E2500
Linksys E3000 (new)
Linksys E3200 (new)
Linksys E4200 (new)
Linksys RV082 (new)
Linksys WRVS4400N
Mikrotik CCR1009 (new)
Mikrotik Cloud Core Router (CCR) CCR1016
Mikrotik CCR1036
Mikrotik CCR1072
Mikrotik CRS109 (new)
Mikrotik CRS112 (new)
Mikrotik CRS125 (new)
Mikrotik RB411 (new)
Mikrotik RB450 (new)
Mikrotik RB750 (new)
Mikrotik RB911 (new)
Mikrotik RB921 (new)
Mikrotik RB941 (new)
Mikrotik RB951 (new)
Mikrotik RB952 (new)
Mikrotik RB960 (new)
Mikrotik RB962 (new)
Mikrotik RB1100 (new)
Mikrotik RB1200 (new)
Mikrotik RB2011 (new)
Mikrotik RB3011 (new)
Mikrotik RB Groove (new)
Mikrotik RB Omnitik (new)
Mikrotik STX5 (new)
Netgear DG834 (new)
Netgear DGN1000 (new)
Netgear DGN2200
Netgear DGN3500 (new)
Netgear FVS318N (new)
Netgear MBRN3000 (new)
Netgear R6400
Netgear R7000
Netgear R8000
Netgear WNR1000
Netgear WNR2000
Netgear WNR2200 (new)
Netgear WNR4000 (new)
Netgear WNDR3700 (new)
Netgear WNDR4000 (new)
Netgear WNDR4300 (new)
Netgear WNDR4300-TN (new)
Netgear UTM50 (new)
QNAP TS439 Pro
Other QNAP NAS devices running QTS software
TP-Link R600VPN
TP-Link TL-WR741ND (new)
TP-Link TL-WR841N (new)
Ubiquiti NSM2 (new)
Ubiquiti PBE M5 (new)
UPVEL Unknown Models* (new)
ZTE ZXHN H108N (new)

Why should this malware be considered important?
The authors (thought to be a group funded by a nation state) of this malware are using it to hijack vulnerable routers (500,000 are known to have been compromised across 54 countries) for possible use in cyberattacks against the Ukraine. Indeed, the malware more recently began seeking out Ukrainian routers specifically. The Ukrainian Secret Service issued a security alert on this on the 23rd of May.

The malware has the ability to do so by utilising previously publicly disclosed (defined) vulnerabilities to gain access and persistence (namely remaining present after the router is powered off and back on) within these routers. Last week the FBI took control of this botnet and are now working to clean up the affected devices.

The malware is very sophisticated and can persist within a router even if the router is powered off and back on (becoming the second malware to have this ability, the first being the Hide and Seek botnet). The malware is made up of 3 stages:

Stage 1: Is responsible for the persistence (mentioned above).
Stage 2: Providing the capabilities of a remote access Trojan (RAT)(defined)
Stage 3: Provides plugins for the RAT to extend it’s functionality.

The malware also has the capability to do the following:

  1. Wipe the firmware (see Aside below for a definition) of routers rendering them useless
  2. Inspect the data traffic passing through the router (with the possible intention of obtaining credentials passing over the wire to gain access to sensitive networks)
  3. Attempt to locate ICS/SCADA devices (defined) on the same network as the router by seeking out port 502 traffic, namely the Modbus protocol (defined) with the option of deploying further malware
  4. Communicate via the Tor network (definition in the Aside below).

How can I protect my devices from this malware?
The FBI are asking anyone who suspects their internet router to be infected to first reboot it (turn on and off the router). This will cause an infected device to check-in with the now under FBI control C&C (command and control, C2 (defined) server to provide them with a better overview of the numbers of infected devices.

To completely remove the malware; reset the device to factory defaults (this won’t harm a non-infected either but please ensure you have the necessary settings to hand to re-input them into the router, your internet service provider (ISP) will be able to help with this). This will remove stage 1 of the malware (stage 2 and 3 are removed by turning the router on an off).

To prevent re-infection: Cisco Talos’ team recommendations are available from this link. Moreover the US CERT provide recommendations here and here. Symantec’s recommendations are provided here (especially for Mikrotik and QNAP devices).

Further advisories from router manufacturers are as follows (their advice should supersede any other advice for your router model since they know their own devices the best):


Further recommendations from Sophos are:

  • Check with your vendor or ISP to find out how to get your router to do a firmware update.
  • Turn off remote administration unless you really need it
  • Choose strong password(s) for your router
  • Use HTTPS website where you can

A very useful and easy to follow step by step walk through of removing this malware by BleepingComputer is available from this link with useful guidance for multiple router models.

Thank you.

New VPNFilter malware targets at least 500K networking devices worldwide : Cisco Talos team

What is firmware?
Firmware is semi-permanent embedded software code that allows a device to carry out its function by having the low-level hardware carry out useful sequences of events.

What is The Onion Router (Tor)?
The Onion Router (Tor) is an open source (defined) project with the goal of protecting your privacy by passing your web browsing activity through a series of anonymous relies spread across the internet. These relays act like proxy servers which encrypt and randomly pass the traffic they receive from relay to relay.

This web of proxies is sometimes referred to as the Dark web (a portion of the internet only accessible using the Tor network). This makes tracing the source of the source almost impossible.

WPA2 KRACK Vulnerability: What you need to know

Last Sunday, the early signs of a vulnerability disclosure affecting the extensively used Wi-Fi protected access (WPA2) protocol were evident. The next day, disclosure of the vulnerability lead to more details. The vulnerability was discovered by  two researchers Mathy Vanhoef and Frank Piessens of the Katholieke Universiteit Leuven (KU Leuven) while examining OpenBSD’s implementation of the WPA2 four way handshake.

Why should this vulnerability be considered important?
On Monday 16th October, the KRACK (key re-installation attacks) vulnerability was disclosed. This vulnerability was found within the implementation of the WPA2 protocol rather than any single device making it’s impact much more widespread. For example, vulnerable devices include Windows, OpenBSD (if not already patched against it), Linux, Apple iOS, Apple macOS and Google Android.

If exploited this vulnerability could allow decryption, packet replay, TCP connection hijacking and if WPA-TKIP (defined) or GCMP (explained) are used; the attacker can inject packets (defined) into a victim’s data, forging web traffic.

How can an attacker exploit this vulnerability?
To exploit the vulnerability an attacker must be within range of a vulnerable Wi-Fi network in order to perform a man in the middle attack (MiTM)(defined). This means that this vulnerability cannot be exploited over the Internet.

This vulnerability occurs since the initial four way handshake is used to generate a strong and unique key to encrypt the traffic between wireless devices. A handshake is used to authenticate two entities (in this example a wireless router and a wireless device wishing to connect to it) and to establish the a new key used to communicate.

The attacker needs to manipulate the key exchange (described below) by replaying cryptographic handshake messages (which blocks the message reaching the client device) causing it to be re-sent during the third step of the four way handshake. This is allowed since wireless communication is not 100% reliable e.g. a data packet could be lost or dropped and the router will re-send the third part of the handshake. This is allowed to occur multiple times if necessary. Each time the handshake is re-sent the attacker can use it to gather how cryptographic nonces (defined here and here) are created (since replay counters and nonces are reset) and use this to undermine the entire encryption scheme.

How can I protect myself from this vulnerability?
AS described in this CERT knowledge base article.; updates from vendors will be released in the coming days and weeks. Apple (currently a beta update) and Microsoft already have updates available. OpenBSD also resolved this issue before the disclosure this week.

Microsoft within the information they published for the vulnerability discusses how when a Windows device enters a low power state the vulnerable functionality of the wireless connection is passed to the underlying Wi-Fi hardware. For this reason they recommend contacting the vendor of that Wi-Fi hardware to request updated drivers (defined).

Links to affected hardware vendors are available from this ICASI Multi-Vendor Vulnerability Disclosure statement. Intel’ security advisory with relevant driver updates is here. The wireless vendor, Edimax also posted a statement with further updates to follow. A detailed but easy to use list of many vendors responses is here. Since I use an Asus router, the best response I could locate is here.

Update: 21st October 2017:
Cisco have published a security advisory relating to the KRACK vulnerability for its wireless products. At the time of writing no patches were available but the advisory does contain a workaround for some of the affected products.

The above updates are software fixes but updates will also be made available for devices in the form of firmware updates e.g. for wireless routers, smartphones and Internet of Things (IoT)(defined) devices. For any wireless devices you own, please check with the manufacturer/vendor for available updates with the above CERT article and vendor response list detailing many of the common vendors.

Thank you.

Internet of Things malware destroys devices

In early April embedded devices powered by Google Android, Linux and FreeBSD (specifically the BusyBox distribution) mainly used as media players and routers came under attack from a previously unseen form of malware.

How does this malware affect compromised devices?
Once compromised the device will cease functioning within seconds; an attack being called a PDoS (Permanent Denial of Service). This occurs since the malware corrupts the devices internal storage and reduces the number of kernel (defined) threads (sequences of independent in progress tasks) from several thousand to just one, causing the devices in progress tasks/work load to halt. Security firm Radware demonstrated this result with a webcam.

How does this malware initially compromise a device?
Since early April four unique versions of this malware (dubbed BrickerBot) have emerged. The first version attempted to compromise Radware’s test device almost 2,000 times within four days with the attacks originating from all over the world. The second and more advanced version uses Tor (The Onion Router) to enable attacks to take place from the Dark web (a portion of the internet only accessible using the Tor network). This makes tracing the source of the attacks almost impossible.

Versions 3 targets further devices while version 4 was active during a very briefly and ceased its activity after 90 attempted attacks. Radware provide more details in their analysis.

The malwares authors seek to gain control of vulnerable devices by attempting to access them over the internet via the Telnet protocol (defined, which uses TCP and UDP ports 23) by entering commonly used usernames and passwords until successful. If your network contains routers or music/media devices using the BusyBox distribution they are potentially vulnerable to this malware. Attackers can use tools such as Shodan (defined) to locate vulnerable devices over the internet and begin an attack.

How can I protect my devices from this malware?
Radware provide five steps you can take to better secure your internet of things (IoT , defined) devices from this malware. They also suggest the use of an IPS (defined) in this related blog post. The above recommendations are especially important since unlike other malware where you can re-format a hard disk and re-install the operating system (defined), this malware permanently damages the device and it will require a replacement.

Thank you.

Linux Routers Potentially Vulnerable To Telnet Worm

In late March ESET security published a blog post detailing how an updated version of an existing malware infection can exploit many consumer broadband routers and wireless access points.

Why Should This Infection Be Considered Important?
If your router becomes infected with this malware it can communicate back to its creator via a command and control (C2) server (defined). Under their control your router can be used for purposes such as a distributed denial of service attack (DDos) attack (defined) among any other action the attackers may choose. An example of a DDoS attack occurring in the past using routers is the subject of this article and this article.

Given that the malware comes to reside on a router by attempting to connect to random IP addresses (defined) that have port 23 open it may only be a matter of time before your router is tested for this open port.

By convention port 23 is used by the now deprecated Telnet (defined) protocol. If your routers firewall (defined) does not block access to this port from external sources the attackers have a favourable opportunity to infect your router since the malware can download various versions customized to the individual CPU architecture used within the router e.g. MIPS, ARM etc. The malware attempts to gain access to your router using a stored list of username and passwords that are commonly used or are used by default by consumer routers. Once access is obtained the malware is downloaded and installed.

How Can I Protect Myself from This Malware?
As discussed in a previous blog post, please follow the recommendations provided by the US-CERT to secure your router. This will involve (among other changes) changing the default username and password of the router (making it much harder for the malware to guess the correct credentials).

Blocking commonly used protocols from being used to access your router (which in this case is the Telnet protocol) using your firewall is explained here. Use of a tool (e.g. Steve Gibson’s ShieldsUP!) to test the effectiveness of your router’s firewall will also provide additional protection against this threat and other threats that may attempt to access your router is discussed here. A guide for using ShieldsUp to do this is here with a video demo here. Scanning your router using Nmap (a more advanced tool) is discussed in this article.

Since many Internet Service Providers (ISPs) block/prevent end-users/consumers from making many changes to their routers, please contact your ISP for advice on how to block port 23 from being accessed externally to protect against the threat discussed in ESET’s blog post.

Thank you.

Blog Post Shout Out December 2015

Earlier this year CloudFlare published an informative blog post detailing how malicious JavaScript (defined) can be used to cause a distributed denial of service attack (DDos)(which is defined within CloudFlare’s post linked to below).

As a preventative measure they also provide a recommendation to enable HTTPS for your website (which CloudFlare also provide as an option). If you are using a self-hosted WordPress installation (namely where WordPress is installed on a server that you manage/administer), this blog post may be of assistance in enabling HTTPS by default (by using HSTS (discussed/defined at length within a previous blog post of mine)).

Given the severity of DDoS attacks I wanted to provide a respectful shout-out to following CloudFlare blog post:

An introduction to JavaScript-based DDoS by Nick Sullivan (CloudFlare)

In addition, earlier this month US-CERT created a useful security alert containing a list of tips for securing your home broadband/fibre optic router/wireless access point. In addition, their alert also links to an updated list of routers with known security vulnerabilities with advice on addressing them:

Securing Home and Small Business Routers (US-CERT)

I hope that the above mentioned blog posts and resources are of assistance to you in defending your website from becoming part of such DDoS attacks and securing your home router/access point against malicious use.

Thank you.