What You Should Know About the iPhone SMS Spoof Attack

A flaw in iPhone security could allow spoofed SMS text messages, but there are some tricks you can use to detect and avoid them.

SMS text messaging is certainly not exclusive to Apple or its iconic iPhone smartphone. But, apparently there is something unique about the way Apple delivers SMS messages that makes the iPhone particularly vulnerable to spoofing or smishing (SMS phishing) attacks.

An iOS security researcher wrote a blog post detailing the discovery. When an SMS text message is sent, part of the header information contains the actual number the message originated from. However, there is also an optional header called the UDH (User Data Header) which allows for a different Reply To address to be entered.

Some mobile platforms display both the actual originating number and the information from the Reply To field, hopefully raising some red flags for the recipient if the two are different. Apples iOS only displays--and responds to--the address specified in the Reply To field.

Why is that a problem? Well, if an attacker knows the phone number of your financial institution, or your Mom, or your boss, he (or she) could send a text message to your iPhone that appears to originate from that number. On an iPhone, the SMS text message would seem to be from a legitimate source, and youd be much more likely to respond, or comply with requests for sensitive information you normally wouldnt share.

Apple responded to Engadget regarding the security flaw with the following statement:

Apple takes security very seriously. When using iMessage instead of SMS, addresses are verified which protects against these kinds of spoofing attacks. One of the limitations of SMS is that it allows messages to be sent with spoofed addresses to any phone, so we urge customers to be extremely careful if they're directed to an unknown website or address over SMS.

The problem with that solution is that iMessage only works between iOS devices. So, unless everyone you might send or receive text messages from is also using an iPhone, iPad, or Mac OS X to communicate with you, iMessage isnt actually a feasible fix.

The security researcher who revealed the flaw summed his blog post up with, Now you are alerted. Never trust any SMS you received on your iPhone at first sight.

That seems fair, but there are some other elements you can use to determine if the message is legitimate or not. First of all, if you receive a message from someone who is not in your iPhone contacts, it generally shows up as the originating phone number as opposed to Mom. As mentioned above, an attacker who knows your moms mobile number may be able to send a spoofed message that appears to be from your mom, but a spoofed message from another number should appear as the number itself even if the message claims to be from your mom.

Second, common sense should play a role here as well. If you and your best friend text regularly about the sports, or politics, or what the plans are for the coming weekend, and you receive a text that just says click this link, you should be suspicious. If your Mom barely knows what text messaging is, and never really uses SMS, it should alert you that something isnt right if you get a message out of the blue asking for money.

SMS text messaging is a great tool, but its certainly not the most secure. Apples implementation of SMS may be more prone to spoofing than other mobile platforms, but you should think twice about clicking links or sharing sensitive information via SMS messaging on any platform.

As smartphones continue to become more mainstream, attackers will continue to seek out ways to find weaknesses and exploit them. And while iOS has so far remained relatively secure compared to other smartphone operating systems, it's by no means perfect. As attackers get more aggressive about targeting smartphones and tablets, the need for cross-device security will only continue to increase.

Join the CSO newsletter!

Error: Please check your email address.
Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by David Jeffers

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

More videos

Blog Posts

Market Place