New PDF-Based Cyber Threat Exploits Mobile Devices

A sophisticated mishing campaign leveraging malicious PDFs poses a threat to organizations across more than 50 countries, according to Zimperium.

mishing (mobile-targeted phishing)
(Image: Adobe Stock / Generated with AI by zong)

An advanced mishing (mobile-targeted phishing) campaign impersonating the United States Postal Service (USPS) and exclusively targeting mobile devices, has been uncovered by Zimperium. The investigation, spearheaded by Zimperium’s zLabs threat research team, reveals an unprecedented method of obfuscation used to deliver malicious PDF files designed to steal credentials and compromise sensitive data.

The campaign exploits the trust that users place in official-looking communications and the PDF format. Cybercriminals embed malicious elements into PDFs, using social engineering tactics to deceive recipients. On mobile devices, where users may have limited visibility into file contents before opening them, the risks of data breaches, credential theft, and workflow disruptions significantly increase.

“Although USPS has no involvement, cybercriminals exploit its trusted name to mislead and target users,” said Nico Chiaraviglio, zLabs Chief Scientist at Zimperium. “This campaign shows the growing sophistication and continued rise of mishing attacks, emphasizing the need for proactive mobile security measures.”

Key Information

USPS mishing
(Source: Zimperium)
  • Campaign Scale: Over 20 malicious PDF files and 630 phishing pages identified, targeting organizations in 50+ countries.
  • Innovative Evasion Techniques: Newly discovered methods obscure malicious links, evading traditional endpoint security solutions.
  • Critical Vulnerability: PDFs used as a vector exploit mobile users’ confidence in the format, posing a significant threat to enterprise security.

Steps For Protection

To protect against SMS and PDF phishing attempts like this, Zimperium recommends following these best practices:

  • Scrutinize Sender Details: Verify the sender’s phone number or email address. Official USPS messages will come from a verified source.
  • Avoid Clicking On Links: Navigate directly to the official USPS website or use their mobile app instead of clicking on embedded links.
  • Inspect PDF Metadata: On a desktop or through a trusted app, review the document properties for unusual or mismatched information.
  • Enable Security Tools: Use advanced mobile threat defense solutions to detect and block phishing attempts.
  • Report Suspicious Activity: If you receive a questionable message claiming to be from USPS, report it at the official USPS phishing page or directly through their support channels.

For a deeper dive into this campaign and how to safeguard enterprises against PDF and mishing threats, read the detailed blog.

Read more business continuity related technology news on Continuity Insights.

Business Continuity, Cyber, Enterprise Risk, Featured, Security, Technology

Business Resiliency, cybercrime, Cybersecurity, Malicious PDFs, Mishing, Mobile Security, Mobile-targeted Phishing, technology, United States Postal Service (USPS), Zimperium

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