Tag Archives: backdoor

Responding to the Asus Live Update Supply Chain Compromise

Earlier last week the security vendor Kaspersky detailed their initial findings from the compromised supply chain of the Taiwanese hardware vendor Asus.

TL DR: If you own or use any Asus laptop or desktop system, please check if your device is affected using the downloadable tool from Kaspersky (which checks the MAC address (defined) of your network card). If you know how to obtain the MAC address of your network card manually you can use the online tool. This is the link for both tools: https://securelist.com/operation-shadowhammer/89992/

If you are affected, contact Kaspersky, contact Asus or use the anti-malware tools to try attempt removal of the backdoor (defined) yourself.

When did this attack take place and what was affected?
This incident took place from June to November 2018 and was initially thought to have affected approximately 60,000 users. This number was later revised to possibly affecting just over a million users. While primarily users in Asia and Russia were targeted; a graph of victim’s distribution by country shows users within South America, Europe and the US. It was later disclosed that mainly Asus laptops were affected by this incident.

What Asus infrastructure was affected?
An older version of the Asus Live Update utility was compromised by unknown attackers so that it would inject a backdoor within the Asus Live Update utility when it was running. The compromised Asus Live Update utility was signed with an older but still legitimate Asus digital signature. The compromised Asus utility was available for download from two official Asus servers.

What were the attacker’s intentions?
Unfortunately, even after extensive analysis it is unknown why the attackers targeted their chosen victim systems or what their eventual goal was. The backdoor would have likely allowed the attackers to steal files of their choice, remote control the system (if the second stage had been installed) and deploy compromised updates to systems which in the case of a UEFI update may have rendered the system unbootable.

It appears the goal of the attackers was to target approximately 600 systems of interest to them with the initial intention to carry the above-mentioned actions. We know it is approximately 600 systems since upon installation the malware would check if the system had a MAC address of interest; if yes it would install the stage 2 download (which unfortunately Kaspersky was unable to obtain a sample of). The server which hosted the stage 2 download was taken offline in November 2018 before Kaspersky became aware of this attack.

If the system was not of interest, the backdoor would simply stay dormant on the system. It’s unclear how the attackers may choose to leverage this in the future (assuming it remains intact on a system which installed the compromised utility).

Do we know who is responsible?
It is not possible to determine with absolute certainty who these attackers were but it is believed it is the same perpetrators as that of the ShadowPad incident of 2017. Microsoft identifies this advanced persistent threat (APT) (defined) group with the designation of BARIUM (who previously made use of the Winnti backdoor).

How have Asus responded to this threat?
Initially when Kaspersky contacted Asus on the 31st of January 2019 Asus denied their servers were compromised. Separately a Kaspersky employee met with Asus in person on the 14th of February 2019. However, Asus remained largely until earlier this week.

On the 26th of March Asus published a notice which contains an FAQ. They issued an updated version (3.6.8) of the Asus Live Update utility. Additionally, they have “introduced multiple security verification mechanisms to prevent any malicious manipulation in the form of software updates or other means, and implemented an enhanced end-to-end encryption mechanism. At the same time, we have also updated and strengthened our server-to-end-user software architecture to prevent similar attacks from happening in the future”.

They have also made available a utility to check if your system was affected. It is downloadable from the above linked to notice.

How can I remove the backdoor from my system if I installed the compromised Asus utility?
While Asus in their announcement recommends a full backup and full reset of your system; for some that may not be a preferred choice. If you use Kaspersky security suite it will very likely easily remove it since they were the first to detect it.

Please which ever approach is more convenient for you.

If you want to leave your system as it is:
I would first recommend a scan of your system with your current anti-malware product. I would then recommend using free anti-malware scanners such as RogueKiller, AdwCleaner and PowerEraser since they use cloud based forensic analysis and compare known safe files on your system with VirusTotal to check if any file has been tampered with or is new/suspicious. It is very unlikely the backdoor could hide from all of these utilities. Yes, this is overkill but will ensure a thorough check.

A link to full original story of this malware is available here.

You use an Asus system; how were you affected?
Since my high-end Core i9 7980 Extreme desktop uses an Asus desktop motherboard (ROG Rampage VI Apex); I ran the Asus utility to check my system; It displayed the message “Only for Asus systems” before closing. I’ll make an educated guess and assume that since the threat mainly affects laptops running this tool on a desktop system resulted in this message.

The offline and online tools from Kaspersky showed no issues with my system. I wasn’t surprised since I don’t use the Asus Live Update utility. Their drivers are available manually from their website and that’s how I stay updated.

I upload every downloaded file for my system to VirusTotal, verify the checksums and digital signatures, use two reputation based scanners on new downloads and have application whitelisting enabled. In summary; my system will be more difficult to compromise.

Thank you.

APT28 Group Distributes First in the Wild UEFI Rootkit

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Update: 6th February 2019
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In mid-January, the IT news website; The Register provided details of an analysis of this threat from the security firm Netscout. They concluded that they believe the malware utilising the UEFI rootkit began as long as 2 years ago:

In addition; the command and control (C2) (defined) infrastructure originating from this threat remains operational but has reduced from 7 servers to 2. The attackers also have further servers and reserved IP addresses ready to use should they need to.

Thank you.

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Original Post:
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In late September; researchers from the security/anti-malware firm Eset discovered the first UEFI (defined) rootkit (defined) being used in the wild (namely being present on computing devices used by the general public in their professional and personal lives).

The APT group known as APT28 (who we discussed before on this blog) has been named as being responsible for this advanced threat being distributed to victim systems located in the Central Europe, Eastern Europe and the Balkans.

Why should this threat be considered important?
While this threat is so far limited to targeting systems in Central Europe, Eastern Europe and the Balkans; it has the potential to set a precedent to dramatically increase the persistence of malware on selected systems. This is due to the fact that to save time malware removal usually involves re-installing the operating system. More advanced users may choose to re-create the MBR/GPT, replace the boot sector and rebuild the BCD. Even more informed users may replace the hard disk to remove the malware. This new threat is significant since all of these steps would not remove it.

Eset researchers discovered that the LoJack anti-theft software which was installed compromised systems was being leveraged to start the attacker’s malware instead by using the Windows registry (defined) to load files with very similar names to that of the legitimate LoJack software. They also located a kernel (defined) driver (defined) being used to write the systems firmware when required. Since this tool was a legitimate tool; it has a valid digital signature. This is significant; otherwise the attacker’s tool would not have worked on a 64 bit Windows system. Should attempts to write to the firmware fail, the malware uses a 4 year old vulnerability CVE-2014-8273 (a race condition (defined)) to bypass the write lock.

Once the firmware has been updated it replaces the original LoJack software files with hijacked versions designed to enable further persistence on the compromised systems, namely a backdoor (defined).

How can I protect myself against this threat?
While it is less likely a threat of this sophistication will become widespread; the steps below will help to defend you against this and similar threats in the future. How this threat establishes an initial foothold on a system was inconclusive by Eset. However exercising caution on the links you click in emails, IMs and social networking should provide some form of prevention. Keeping your system up to date should also prevent a drive by download (defined). However I will detail more specific defensive steps below:

Eset determined that this threat can be prevented from affecting a system by enabling the Secure Boot hardware security feature (if your system has this feature available; most systems manufactured from 2012 onwards do). Any system with a certified Windows 8 or Windows 10 badge on the outside will have Secure Boot enabled with no action required from you. Secure Boot works even better when paired with Intel BootGuard (corporate users are more likely to use/enable this feature).

If the rootkit had affected the system described above it would have then refused to boot due to Secure Boot being enabled. It’s important to clarify that Secure Boot won’t prevent the infection/tampering but it will prevent that tampering from starting the system for use as normal.

Secure Boot was added to Windows 8.0 in 2012 to prevent unsigned components (e.g. rootkits) from affecting a system so early in the boot process that anti-malware software would be unable to detect or prevent that component from obtaining a privileged level of access over the system.

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Keeping the UEFI firmware of your system up to date will assist with resolving known vulnerabilities within the firmware. Patching known firmware vulnerabilities makes your system less vulnerable to low level attacks such as this. Please only install UEFI firmware updates from your system vendor. Check the vendor’s website or contact them to determine if you need a UEFI firmware update and how to install it. If possible/available verify the checksum (defined) of the file you download matches the vendors provided checksum. I use the word available above since not all vendors provide checksums of the firmware updates they distribute which would allow you to verify them.

More recent Intel motherboards (defined) are not vulnerable to the race condition by Eset in their paper (more details available here). These modern chipsets feature a Platform Controller Hub (present in Intel’s Series 5 chipsets and later (available circa 2010 onwards).

If you know of a system affected with such a low level threat you may be able to update the UEFI firmware with a known safe version from the vendor but this is not guaranteed to work. Replacing the hardware will be a more reliable alternative.

Thank you.

Blog Post Shout Out: Cisco IOS XE and Drupal Security Updates

I wish to provide a respectful shout to the following security advisories and news articles for their coverage of critical security vulnerabilities within Cisco IOS XE and the Drupal CMS (defined) released on the 28th and 29th of March respectively.

The backdoor (defined) account being remediated within the Cisco IOS XE update could have allowed an unauthenticated attack to remotely access the Cisco router or an affected switch and carry out any action allowed by privilege level 15

Meanwhile the Drupal vulnerability (dubbed “Drupalgeddon2”) is rated as highly critical since the vulnerability is both remotely exploitable and easy for an attacker to leverage allowing the attacker to carry out any action they choose.

Please follow the advice within the below linked to advisories and update any affected installations of these products that your organisation may have:

March 2018 Semi-annual Cisco IOS and IOS XE Software Security Advisory Bundled Publication

Cisco Removes Backdoor Account from IOS XE Software (includes mitigations if patching is not possible) by Catalin Cimpanu (Bleeping Computer)

Drupal core – Highly critical – Remote Code Execution – SA-CORE-2018-002

Drupal Issues Highly Critical Patch: Over 1m Sites Vulnerable by Tom Spring (Kaspersky ThreatPost)

Thank you.

DoublePulsar exploit: victim devices are widespread

Last month the hacking group known as the Shadow Brokers made available a set of exploits (this appears to be their last remaining set). These exploits allegedly came from the NSA. A full list of the exploits is available here. Microsoft’s analysis of the exploits made which applies to their products and which security updates resolve them are available here.

What is DoublePulsar and how does it affect a system?
The exploit from this recently released collection which targets the Windows SMB Server component of Windows is known as DoublePulsar. It is a kernel mode (or ring zero (defined)) exploit which provides an attacker with full control over an affected system as well as providing a backdoor (defined).

It is also allows the execution of shellcode (defined) and the downloading of further malware. A complete list of it’s capabilities is available from Symantec’s analysis.

This threat is being called similar to the MS08-067 vulnerability from October 2008 which lead to widespread installation of the Conficker malware (which still persists today). That article estimates this vulnerability will be with us for many years to come. In my professional career I still see large numbers of servers and workstations not patched against the MS08-067 vulnerability even after all these years. The exploits made available by the Shadow Brokers have been made easy to use by others posting YouTube videos and documentation of how to use them. Security researchers are tracking the spread of this malware here , here and here.

How can I protect myself from this threat?
Preventing a compromise by this threat:

If your servers or workstations have Windows Server 2008 or Windows Vista (respectively) or newer installed, please install Microsoft’s security update MS17-010 as soon as possible. As a defense in-depth measure (defined)(PDF), please also consider blocking port 445 from being accessed externally (since this is unlikely to be the last SMB exploit we see).

Please note, Windows Vista systems are also no longer supported and you should consider upgrading (if you are not already in the process of doing so). Windows Server 2008 will be supported until the 13th of January 2020.

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Update: 19th May 2017:
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With the rapid propagation of the WannaCry ransomware, Microsoft made available the MS17-010 update for Windows XP, Windows Server 2003 and Windows 8.0. The updates for these out of support operating systems are available from Microsoft’s blog post.

Once the update is installed, if your servers or workstations have Window Server 2003 or Windows XP (respectively) installed, please block port 445 (the Windows SMB protocol port) from being accessed from an external network (as previously recommended by US-CERT and mentioned in a past blog post of mine).

In addition to blocking port 445 as mentioned above, I would also suggest the following:

If you can, segregate your vulnerable devices (including devices within your network perimeter) so they don’t expose the following ports:

  • TCP port 445 with related protocols on UDP ports 137-138
  • TCP port 139
  • Also disable SMBv1 (it’s a deprecated protocol)
  • Please also block the Remote Desktop Protocol (RDP) port 3389 (defined) at the entry point to your corporate to prevent the spread of this malware as recommended by the US CERT.

To check if your system has been compromised by Double Pulsar, you can use this tool.

Removing the threat from a compromised system:
You can remove the infection simply by shutting the system down since the malware does not persist after a reboot. You can then patch the vulnerability and block access to port 445 to prevent the malware from returning (both as mentioned above).

Thank you.

Malware uses DNS protocol for command and control

In early March two Cisco Talos security researchers Edmund Brumaghin and Colin Grady released details of a multi-stage trojan horse which communicates with it’s creator(s) using the Domain Name Service (DNS)(defined) protocol.

Since DNS is a widely used essential protocol it is often allowed to pass through corporate and personal firewalls. The source of the malware is an email containing an attachment reportedly secured with McAfee. The attachment is a Microsoft Word document which when opened requests to enable macros (defined). If the user enables macros the macros unpacks a Microsoft PowerShell script (a computer programming language usually used for automating system administration tasks) which forms the second stage of the attack.

Next the script checks if currently logged in user has administrator rights for their Windows account and checks the installed version of PowerShell. The script then adds a backdoor (defined). If the earlier check for administrative privileges was positive the backdoor will persist after restarting or powering off the system. This backdoor uses DNS to receive and carry out commands from it’s creators.

While analysing this threat, the above mentioned security researchers did not witness the malware receiving DNS commands due to its targeted nature.

How can I protect myself from this threat?
Sine this malware arrives via email, please verify the emails you receive are genuine and not attempting to deliver malware. SANS recently provided extra advice on this (March 6th : source)

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Don’t Trust Links Sent in Email Messages March 6, 2017
A common method cyber criminals use to hack into people’s computers is to send them emails with malicious links. People are tricked into opening these links because they appear to come from someone or something they know and trust. If you click on a link, you may be taken to a site that attempts to harvest your information or tries to hack into your computer. Only click on links that you were expecting. Not sure about an email? Call the person to confirm they sent it.
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In addition if you inspect network traffic within your corporate network, please consider adding DNS to the list of protocols analysed. Attackers are likely to leverage this widely allowed protocol for command and control (defined) going forward.

Thank you.

Disclosed Microsoft Zero Day Under Attack By APT Group

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Update: 8th November:
The Microsoft zero day vulnerability discussed in this post has now been patched. Please refer to this post for the appropriate information and download links.

Thank you.

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Original Post:
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Earlier this week Google publicly disclosed (defined) details of a new zero day (defined) vulnerability affecting supported versions of Windows up to Windows 10. Fortunately, the disclosure only included minimal details.

Why Should These Issues Be Considered Important?
The vulnerability disclosed by Google could result with an attacker being able to elevate their privileges (defined) on an affected system. However, when used in combination with a previously patched Adobe Flash Player vulnerability (reference previous post) this could result in a Windows system under your responsibility or in your ownership to have a backdoor (defined) installed.

Some good news is that this new exploit primarily targets organisations that operate in the following sectors (thus all other organisations are at somewhat reduced risk): government, intelligence or military organisations.

The nature of the backdoor is the decision of the attacker but would usually include a means of remaining persistent on the system and allowing the attacker to remote access the infected system. This backdoor can then be used to move data of the attacker’s choice off the affected system. The APT group known as STRONTIUM by Microsoft (other aliases used in the wider cyber security industry are APT28, also aka Sofacy aka Fancy Bear aka TsarTeam aka Sednit aka PawnStorm). STRONTIUM is also known for moving laterally throughout the network which they compromise (where the pass the hash (PtH) (defined) technique is the method of choice to do so).

How Can I Protect Myself From This Issue?
While a patch from Microsoft is in progress (scheduled for release on the 8th of November): follow safe email guidelines namely don’t click on unexpected/unsolicited links or open potentially dangerous email attachments to prevent the execution (carrying out of) the exploits actions in the first instance.

If you use the Microsoft Edge or Google Chrome web browsers the exploit for the local elevation of privilege vulnerability will be mitigated. This is due to Chrome’s sandbox (defined) blocking the use of API (defined) calls to the win32k.sys driver (defined). This in addition to its existing mitigations when installed on Windows 10 which I previously discussed.

Microsoft Edge on the other hand implements Code Integrity to prevent the next steps of exploitation.

To protect endpoints within your organisation you could consider utilising the logging capabilities of Microsoft EMET and Systinternals’ Sysmon by processing their logs using a SIEM (defined) and taking action when that SIEM a alerts you to suspicion activity. This is especially true since this exploit can occur from within web browsers, the Java JRE, Microsoft Word and Microsoft PowerPoint (namely that these applications are used to open suspicious/untrusted files).

My thanks to a colleague (you know who you are!) for compiling very useful information for this blog post.

Thank you.

Juniper Issues Emergency Security Updates For VPN Devices

On the 17th of December Juniper Networks released a security advisory which detailed 2 critical security issues (these have been assigned 2x CVE numbers (defined) within their NetScreen devices which offer VPN (Virtual Private Networks) (defined) access. Juniper have released emergency security updates to address these issues.

Why Should These Issues Be Considered Important?
The first issue assigned CVE-2015-7755 could allow an attacker to remotely access your Juniper VPN device using SSH or telnet. They could do so by accessing your device using either of these protocols. They will then receive a logon prompt however due to this issue they can enter any username and since the password has been publically disclosed they would then obtain access to your device with the highest privileges available. This is an extremely serious backdoor (defined) that an attacker can easily exploit.

The second vulnerability designated CVE-2015-7756 could allow an attacker who can capture your VPN network traffic to decrypt that encrypted traffic and read all of it’s contents. In addition, there is no means of detecting if this second vulnerability has been exploited.

Juniper NetScreen devices using the operating system versions mentioned below have been confirmed to have been affected by these issues:

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The first issue mentioned above (the administrative access issue) affects the following versions of ScreenOS (the operating system that powers these Juniper devices):

ScreenOS 6.3.0r17 through 6.3.0r20
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The VPN decryption issues affects ScreenOS 6.2.0r15 through 6.2.0r18 and 6.3.0r12 through 6.3.0r20
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Finally, there are theories with compelling evidence of how this backdoor code came to be present within Juniper’s products in the first instance. The definitive answer does not appear to be completely clear at this time. If you wish to read more on this aspect of these security issues, please find below further references:

Juniper Finds Backdoor That Decrypts VPN Traffic by Michael Mimoso (Kaspersky ThreatPost)
Juniper Backdoor Password Goes Public by Michael Mimoso (Kaspersky ThreatPost)
Juniper Backdoor Picture Getting Clearer by Michael Mimoso (Kaspersky ThreatPost)
On the Juniper backdoor by Matthew Green (John Hopkins University)
Who were the attackers and how did they get in? by Jeremy Kirk (IDG News Service)
CVE-2015-7755: Juniper ScreenOS Authentication Backdoor by H. D. Moore (Rapid7)
“Unauthorised code” on Juniper firewalls gives attackers admin access, decrypts VPN traffic by Graham Cluley (writing on behalf of BitDefender)

How Can I Protect Myself From These Issues?
As directed within Juniper’s security advisory if you are using the affected Juniper devices within your corporation or small business, please apply the necessary updates as soon as possible since these issues are very serious. Download links for these updates are provided within the above mentioned security advisory. Juniper also supplies additional best practice within that advisory.

SNORT IDS/IPS (defined) and Sagan (an open source log analysis engine) rules to detect the first issue (administrative access) being exploited are provided in Rapid7’s blog post. That blog post also contains advice if you are having an issue installing the updates to address these issues.

Thank you.

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Note: I am currently working on more upcoming content for this blog. Since this will be my final post before the 25th of December I wanted to wish you and yours a safe and very Merry Christmas / Happy Holidays. I will return later this week with more blog posts.

Thanks again.