Over the last week, we have observed an increase in phishing emails claiming to be from LinkedIn Support. The body of the email claims that irregular activities have prompted a “compulsory security update” for the recipients’ LinkedIn account.

“Irregular activities”

The email goes on to say that in order to secure their account, the recipient needs to download the attached form (an HTML attachment) and follow the instructions.



Figure 1. LinkedIn phishing email

The attachment is a copy of the real LinkedIn.com website. However, the website’s source has been modified, so if the recipient uses this web page to sign in to their LinkedIn account, their credentials will be sent directly to the attacker.



Figure 2. Local copy of LinkedIn.com’s website



Figure 3. Modified source sends LinkedIn credentials to attacker

Evasion techniques

Curiously, the email uses a lowercase I instead of a capital i when spelling “LinkedIn”. The difference in characters is indiscernible to the eye and functions as a way to evade mail filters.

However, the most important technique used here is the HTML attachment. This method bypasses browser blacklists that often flag suspicious websites to help prevent users from being phished. You can learn more about phishing attacks using HTML attachments from our previous blogs on the topic.

Security tip: Use two step verification

LinkedIn users should consider turning on two-step verification, a true “security update” that provides an extra layer of security. With two-step verification enabled, even if a user’s credentials are compromised, an attacker would not be able to login without having access to the user’s mobile phone.

To learn more about LinkedIn’s two-step verification, please visit its help center.