Phishing Attackers Are Abusing WeTransfer to Evade Email Gateways

By Jake Longden

The Cofense Phishing Defense Center has observed a wave of phishing attacks that utilize the legitimate file hosting site WeTransfer to deliver malicious URLs to bypass email gateways. The attacks span major industries like banking, power, and media. Here’s how they work.

Email Body:

The email body is a genuine notification from WeTransfer which informs the victim that a file has been shared with them. The attackers utilise what appears to be compromised email accounts to send a genuine link to a WeTransfer hosted file. As these are legitimate links from WeTransfer, this allows them to travel straight through security checks at the gateway.

WeTransfer allows for the addition of a note to the email to clarify why the file was sent. Here, the threat actor will often write a note stating that the file is an invoice to be reviewed. This is a commonly observed phishing technique to pique the user’s interest.

Fig 1. Email body

Phishing Page:

When the user clicks on the “Get your files” button in the message body, the user is redirected to the WeTransfer download page where a HTM or HTML file is hosted and thus downloaded by the unsuspecting victim. When the user opens the .html file, he or she is redirected to the main phishing page.

Fig 2. WeTransfer Hosted file

In the final stage of the attack, victims are asked to enter their Office365 credentials to login. More often than not, we see a Microsoft Service being targeted, however we have observed other targeted brands.

Fig 3. Phishing Page

Gateway Evasion

As WeTransfer is a well-known and trusted file hosting system, used to share files too large to attach to an email, these links will typically bypass gateways as benign emails, unless settings are modified to restrict access to such file sharing sites. The PDC has observed this attack method to bypass multiple gateways. These include ProofPoint, Office365 Safe Links,  and Symantec.

Useful Resources for Customers

Description
Triage Yara rule: PM_WeTransfer_File_Download
PhishMe Templates: “File Transfer”
Cofense Intelligence: https://www.threathq.com/p42/search/default#m=26412&type=renderThreat 


Other Ways Cofense Can Help

The Cofense Phishing Defense Center identifies active phishing attacks in enterprise environments. Learn how our dedicated experts provide actionable intelligence to stop phishing threats.

75% of threats reported to the Cofense Phishing Defense Center are credential phish. Protect the keys to your kingdom—condition end users to be resilient to credential harvesting attacks with Cofense PhishMeTM.  Our solution offers a phishing simulation to protect against file-transfer attacks like the one described in this blog.

According to the Cofense Phishing Defense Center, over 91% of the credential harvesting attacks they identify bypassed email gateways. Remove the blind spot—get visibility of attacks with Cofense ReporterTM.

Quickly turn user reported emails into actionable intelligence with Cofense TriageTM. Reduce exposure time by rapidly quarantining threats with Cofense VisionTM.

Attackers do their research. Every SaaS platform you use is an opportunity for attackers to exploit it. Understand what SaaS applications are configured for your domains—do YOUR research with Cofense CloudSeeker.

Thanks to our unique perspective, no one knows more about current REAL phishing threats than Cofense. To raise your understand, read the 2019 Phishing Threat & Malware Review.

 

All third-party trademarks referenced by Cofense whether in logo form, name form or product form, or otherwise, remain the property of their respective holders, and use of these trademarks in no way indicates any relationship between Cofense and the holders of the trademarks.

Under the Radar – Phishing Using QR Codes to Evade URL Analysis

Phishing attacks evolve over time, and attacker frustration with technical controls is a key driver in the evolution of phishing tactics.

In today’s modern enterprise, it’s not uncommon for our emails to run the gauntlet of security products that wrap or scan embedded URLs with the hope of finding that malicious link. Products like Proofpoint URL Defense, Microsoft Safe Links, and Mimecast URL Protect hope to prevent phishing attacks by wrapping or analyzing URLs.  These technologies can only be effective IF they can find the URLs in the first place.

Fast forward to this week where our Phishing Defense Center™ stopped a phishing campaign aimed at customers in Finance. The analysis below outlines the attacker’s use of a URL encoded in a QR code to evade the above-named technologies.  While you’ve probably seen QR codes in your everyday life, this might be the first time you are seeing QR codes used as a phishing tactic.

The Phish:

The email itself is relatively simple. It poses as a pseudo SharePoint email with the subject line: “Review Important Document”. The message body invites the victim to: “Scan Bar Code To View Document”. The only other visible content is a tantalizing QR code that a curious user may be tempted to scan.

Figure 1, Email Body

The message body in plain text consists of several basic HTML elements for styling and an embedded .gif image file of the QR code. Very basic, but very effective.

When the QR code is decoded we can see that that it contains a phishing URL: hxxps://digitizeyourart.whitmers[.]com/wp-content/plugins/wp-college/Sharepoint/sharepoint/index.php

Most smartphone QR code scanner apps will instantly redirect the user to the malicious website via the phone’s native browser. In this case the victim would be redirected to a SharePoint branded phishing site. The victim is then confronted with options to sign in with AOL, Microsoft, or “Other” account services. While this sounds like a simple phish, there is a more nefarious tactic in play: removing the user from the security of a corporate business network.

Figure 2, Phishing site

Standard Security Controls Circumvented:

By enticing the victim to pull out their smartphone and scan the QR code the attacker manages to evade standard corporate security controls. Secure email gateways, link protection services, sandboxes, and web content filters no longer matter because the user is now interacting with the phishing site in their own security space: their mobile phone. And yes, the phishing site is optimized for mobile viewing. Here’s a glance at what the site looks like on a smartphone:

Figure 3, Phishing page viewed on phone

Though the user may now be using their personal device to access the phish, they are still in the “corporate” mindset as the original email was received at their business email address. Therefore, it is highly likely that the victim would input their corporate account credentials to attempt to access this “document”. 

Gateway Evasion:

This attack was observed passing through an environment utilizing Symantec Messaging Gateway. When scanned, the message was deemed “Not spam” by the system as seen in Fig 4 below.

Figure 4, Email Header Snippet

Conclusion:

In the past QR codes were reserved for geeks on the bleeding edge of technology. Today we interact with QR codes more and more as we cut the cord on cable, setup home internet devices, transact crypto currencies, etc…  Will QR codes be a common phishing tactic of the future? Time will tell.  But THIS phishing attack that snuck past best in class phishing technologies was only stopped by an informed, in tune human, who reported it with Cofense Reporter ™ , so that their security teams could stop it.

Today over 90% of phishing threats observed by the Cofense Phishing Defense Center ™ bypassed secure email gateways. Condition users to be resilient to evolving phishing attacks with Cofense PhishMe ™ and remove the blind spot with Cofense Reporter.

 

All third-party trademarks referenced by Cofense whether in logo form, name form or product form, or otherwise, remain the property of their respective holders, and use of these trademarks in no way indicates any relationship between Cofense and the holders of the trademarks.

Phishing Attacks on High Street Target Major Retailer

By Jake Longden

The Cofense Phishing Defense Center™ has observed a phishing campaign that purports to be from Argos, a major retailer in the UK and British High Street. During 2018, Argos was the subject of a large number of widely reported phishing scamsi; this threat specifically targets Argos customers for their personal information and looks like a continuation of what was seen last year.

With the goal of stealing your store credit card and login information, here’s how it works:

All third-party trademarks referenced by Cofense™ whether in logo form, name form or product form, or otherwise, remain the property of their respective holders, and use of these trademarks in no way indicates any relationship between Cofense and the holders of the trademarks.

Fig 1. Email Body

Email Body:

The message itself follows a standard phishing template to inform the user that their account has been restricted and that user sign in is required for verification. The use of bad grammar and typos are a dead giveaway that this email communication is not genuine.

Message body in plain text:

In reviewing the body of the email, we see the hyperlink for “Sign into your account” which directs the potential victim to: hxxps://www[.]argos[.]co[.]uk[.]theninja[.]gknu[.]com/www[.]argos[.]co[.]uk/account-login/

The attacker repeatedly used the string of the legitimate Argos site in the URL, both as part of the subdomains, and as a subdirectory. This was an attempt to mask the true source, and to lure the victim into trusting the legitimacy of the website.

Upon examination, we see that the link is wrapped by a URL filtering service.

href="hxxps://clicktime[.]symantec[.]com/3AuyExDNpRSjkQbgT2gXygH6H2?u=hxxps://www[.]argos[.]co[.]uk[.]theninja[.]gknu[.]com/www[.]argos[.]co[.]uk/account-login/" target="_blank" rel="noopener"><span class="ox-dad7652f0e-m_609589041267919212link-blue ox-dad7652f0e-m_609589041267919212MsoHyperlink ox-dad7652f0e-m_609589041267919212MsoHyperlinkFollowed">SIGN
INTO YOUR ACCOUNT

Fig 2. Email Body in Plain Text

 

Email Headers:

Analysis of the headers indicates that the “from” address is spoofed; the “reply to” field contains the address ‘no-reply[@]creativenepal[.]org’, which does not match ‘no-replays[@]multitravel.wisata-islam[.]com’.

Research on the ‘multitravel.wisata-islam’ domain failed to produce relevant data and reinforces the suspicion that the address is spoofed. At the time of analysis, we were unable to resolve an IP address, or load the domain.

From: <no-replays[@]multitravel[.]wisata-islam[.]com>
To: <[email protected]>
Subject: [WARNING SUSPECTED SPAM]  [WARNING SUSPECTED SPAM]  Please make sure
 you complete the form correctly.
Thread-Topic: [WARNING SUSPECTED SPAM]  [WARNING SUSPECTED SPAM]  Please make
 sure you complete the form correctly.
Thread-Index: AQHVIXUk7CjiCOKjHEyntcvh4etMFg==
Date: Wed, 12 Jun 2019 23:18:17 +0000
Message-ID: <[email protected]>
Reply-To: <“:no-reply”[@]creativenepal[.]org>

Fig 3. Email Headers

Phishing Page:

Once the user clicks on the “Sign into your account” hyperlink, they are redirected to a convincing imitation of the true Argos login page requesting the victims’ Username and Password.

This then leads the user to a second page, where the user is requested to supply details for their Argos store credit card account. This page follows the standard format for regular credit/debit cards with one key difference: the additional request for a ‘Card Amount’. This request is specific to the Argos Card as referenced in the copy: “The Argos Card lets you shop at Argos, with flexible payment plans that give you longer to pay” (see: https://www.argos.co.uk/help/argos-card/apply). This deviates from standard forms by asking the user for their credit limit.

 

 

Fig 4. Phishing Page

Gateway Evasion:

This campaign has been observed to pass through the ‘Symantec Messaging Gateway’.

We can see the influence of the Email gateway which injected ‘Warning Suspected Spam’ headers to the Subject Line and incorrectly presented this phish as a benign marketing email, and not a phishing attempt.

Conclusion:

To help protect against this type of credential phish, Cofense PhishMe™ offers a template called “Account Limitation” in order to improve phishing awareness training.

This credential phish eluded gateways and was actually mis-identified as harmless marketing spam. In fact 75% of threats reported to the Cofense Phishing Defense Center are Credential Phish. Protect the keys to your kingdom – condition end users to be resilient to Credential Harvesting attacks with Cofense PhishMe.

 

All third-party trademarks referenced by Cofense™ whether in logo form, name form or product form, or otherwise, remain the property of their respective holders, and use of these trademarks in no way indicates any relationship between Cofense and the holders of the trademarks.

i Google Search “Argos Data Breach 2018”

Houdini Worm Transformed in New Phishing Attack

By Nick Guarino and Aaron Riley

The Cofense Phishing Defense Center™ (PDC)  and Cofense Intelligence have identified a new variant of Houdini Worm targeting commercial banking customers with campaigns containing either URLs, .zip, or .mht files. This new variant is named WSH Remote Access Tool (RAT) by the malware’s author and was released on June 2, 2019. Within five days, WSH RAT was observed being actively distributed via phishing. Figure 1 shows an example message from this campaign.

The Zombie Phish Is Back with a Vengeance

Keep a close on your inboxes—the Zombie Phish is back and it’s hitting hard.

Last October, on the eve of Halloween, the CofenseTM Phishing Defense CenterTM reported on a new phishing threat dubbed the Zombie Phish. This phish spreads much like a traditional worm. Once a mailbox’s credentials have been compromised, the bot will reply to long-dead emails (hence, Zombie) in the inbox of the infected account, sending a generic phishing email intended to harvest more victims for the Zombie hoard.