Aiman Al-hadhrami Facebook Vulnerability

Security Report: Facebook Vulnerability Allows Remote Attacker Deception and Phishing Attacks

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Visual Trust, Hidden Threat: Facebook Preview Flaw Enables Sophisticated Phishing Attacks

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Overview

Inconsistent handling of link previews in Facebook's mobile application introduces a subtle yet powerful logic flaw. When a user pastes a URL while composing a post or comment, Facebook automatically generates a preview using Open Graph metadata (title, image, description). However, if the original URL is injected before posting, the preview does not update — resulting in a mismatch between the displayed content and the actual link destination.

This silent failure allows attackers to embed malicious links behind trusted-looking previews, increasing the likelihood that users will click and be exposed to phishing, malware, and data theft. The flaw aligns with CWE-451: UI Misrepresentation of Critical Information, and also relates to CWE-345 (Insufficient Verification of Data Authenticity), highlighting weaknesses in Facebook's UI state and trust validation logic.

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Exploit Scenario – Link Preview Mismatch on Facebook Enables Highly Effective Phishing Attacks

Example:

An attacker creates a Facebook post and begins by pasting a legitimate URL — for example:
https://www.afro.who.int/countrie/news/hope-and-healing-integrated-free-surgical-camp-offers-relief-zimbabweans

Facebook automatically generates a trusted preview, including the World Health Organization's logo, a headline about free medical procedures, and a professional image, creating visual trust and a strong sense of credibility.

Before publishing, the attacker injects a malicious URL into the original one, such as:
https://2u.pw/Semzr

Facebook does not regenerate the preview. As a result, the post still displays the trusted WHO preview, while the actual link silently points to a phishing site.

Impact

This flaw enables attackers to:

• Leverage Facebook’s preview system to trick users into trusting malicious links.
• Exploit visual credibility by displaying previews from legitimate sources (WHO, banks, governments, etc.).
• Redirect users to phishing pages where they may:
  • Enter sensitive personal or medical data.
  • Submit banking credentials or login information.
  • Download malware on mobile devices.
• Violate user trust, especially among vulnerable populations seeking health, aid, or financial services.
• Attackers can use Facebook ads to target vulnerable people seeking free surgeries, boosting phishing effectiveness.

Real-World Consequence: A Patient May Suffer or Even Die

Imagine a vulnerable person — perhaps a patient in urgent need of free life-saving surgery — who comes across the post and believes it's from the World Health Organization. Trusting the visual preview, they click and submit personal health information to a fake site.

• The result? Their real medical request goes unanswered.
• They lose valuable time chasing a fake opportunity.
• Their condition may deteriorate rapidly, and in extreme cases, this delay could lead to death.

This transforms the flaw from a technical issue into a life-threatening deception.

Why It’s Critical

This is not just a design oversight — it's a logic flaw with dangerous implications:

• The preview and actual destination do not match, creating a false sense of safety.
• Facebook’s preview system is abused as part of the attack vector.
• Victims are more likely to trust and click the link — especially when desperate for help.

This significantly increases the success rate of phishing campaigns and can lead to identity theft, healthcare fraud, and real harm to human life.

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Facebook UI-Based Link Preview Vulnerability Report — Justification & Scope

1. User Interaction Is Expected and Routine

The attack requires no unusual or non-standard user behavior. A Facebook user simply clicks a link within a post — a natural, expected action that aligns with standard engagement patterns on the platform.

This clearly qualifies as “likely user interaction” under Facebook's vulnerability assessment guidelines.

2. Native UI Deception — Not External Social Engineering

This vulnerability results from a design flaw in Facebook’s link preview system. When a malicious link is posted, Facebook automatically generates a trusted visual preview that may misrepresent the actual destination.

• The deceptive element is embedded within Facebook’s own UI.
• The attacker does not need to craft any off-platform tricks or manipulate the user externally.
• The mismatch between the preview and real link is generated by Facebook’s logic, not through external social engineering.

3. Clearly Within Facebook’s In-Scope Criteria

Design or implementation issues that may compromise the security of Facebook users are in scope according to Facebook's vulnerability disclosure policy.

This issue aligns with that scope because it:

• Abuses Facebook’s trust model and branding.

• Enables phishing, credential theft, or malware delivery.

• Occurs entirely within platform-native features, without bypassing technical controls or requiring complex exploitation.

4. Reproducible with a Clear Technical Root Cause

The behavior is consistently reproducible by creating posts that use a specially crafted link structure. The preview renders misleading information automatically — the technical root cause lies in how Facebook parses and presents preview metadata.

5. Real-World Impact Through Trust Exploitation

This issue has serious real-world implications, enabling attackers to abuse Facebook’s brand reputation and preview system to make harmful links appear legitimate.

This opens the door to large-scale abuse scenarios including:

• Targeted phishing campaigns

• Fraudulent services

• Drive-by malware infections

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Vulnerability Scope: Facebook Mobile App Only

During analysis, this behavior was observed exclusively in the Facebook mobile application. When tested via the web interface, the platform either removes the preview upon URL injection or regenerates it based on the new link. This indicates that the flaw is likely rooted in client-side caching and UI state persistence within the mobile app.

This increases risk significantly — users on mobile platforms are less likely to manually verify URLs, and more likely to trust visual previews.

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Context & Cross-Platform Comparison

During testing, the same steps were reproduced across several popular messaging and social media platforms, including X (formerly Twitter), Threads, Telegram, Signal, and WhatsApp — In all of these platforms, the link preview was correctly updated when the original URL was modified prior to publishing. This behavior ensures consistency between the displayed preview and the actual link destination, thereby reducing the risk of user deception.

In contrast, this unexpected and inconsistent behavior was only observed on the Facebook mobile application (and one other unspecified app). This strongly suggests that the issue is the result of a platform-specific oversight in Facebook's mobile preview handling logic, rather than a technical limitation.

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Security Risks & Real-World Impact

This flaw enables several high-impact exploitation scenarios:

• Legal issue: Using previews based on content from trusted institutions, companies, or organizations such as the WHO may be exploited for phishing or deception and could lead to legal issues.

• Exploitation via Paid Ads: Attackers can boost the reach of malicious posts by promoting them as paid ads on Facebook. This increases visibility, adds perceived legitimacy, and allows precise targeting of vulnerable users, making phishing attacks far more effective and dangerous.

• Phishing & Credential Harvesting: Attacker crafts a post with a preview of a legitimate service (e.g., PayPal.com), then replaces the link with a phishing site. The preview remains trustworthy, increasing click-through and capture rates.

• Theft of Sensitive Information: Redirect victims to fake banking, healthcare, or government portals that harvest login credentials, identity documents, or health data.
  

• Malware Delivery: Clicking on the misleading link can redirect to drive-by download pages or exploit kits, leading to ransomware, spyware, or keyloggers.
  

• Surveillance & Espionage: Journalists, executives, or political targets may be lured into clicking links that activate device-level spyware or tracking beacons.

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Technical Summary

• Facebook generates link previews using Open Graph metadata.
• The preview is cached at the moment the first URL is pasted.
• Injecting a malicious URL does not invalidate the preview.
• The final published post contains:
  • A preview from the first (legitimate) URL
  • A link pointing to a  malicious destination

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Recommendations to Facebook

• Invalidate previews whenever the link is injected before publishing.
• Re-fetch metadata dynamically based on the final URL.
• Display a clear warning if the preview and destination URL mismatch.
• Provide users a way to inspect the true destination before clicking.

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Related CWE and CAPEC Classifications

• CWE-451 – User Interface Misrepresentation of Critical Information

• CWE-345 – Insufficient Verification of Data Authenticity

• CAPEC-98 – Phishing

• CAPEC-125 – URL Manipulation

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Proof of Concept

A full technical report, including a video demonstration, was submitted to Meta.

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Responsible Disclosure:

This vulnerability was discovered and responsibly reported by independent cybersecurity researcher Aiman Al-Hadhrami, in accordance with ethical disclosure standards. It was privately disclosed through Meta’s bug bounty program on 3 July 2025. [Ticket Numbers: 25037377595865726]. Meta appreciated the report and valued the efforts.

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Research Ethics & Statement:

This research was conducted under the principle of responsible disclosure.

No user data was accessed, and no harm was caused to Facebook infrastructure or members.

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Conclusion

This UI inconsistency in Facebook’s mobile app presents a significant security vulnerability, enabling covert phishing attempts, malware distribution, and sophisticated social engineering attacks. Though subtle in appearance, the flaw undermines the fundamental trust model between what users see and where they are actually directed.

Addressing this issue demands prompt and deliberate action, including critical changes to how the platform manages link preview caching and URL validation. Failure to act leaves users exposed to serious security threats and undermines trust in the platform’s integrity.

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Aiman Al-Hadhrami – Independent Cybersecurity Researcher

Aiman Al-hadhrami LinkedIn vulnerability

Security Report: link Preview Update Failure on LinkedIn Enabling Attacker Deception and Phishing Attacks

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LinkedIn Link Preview Mismatch: A Gateway to Deception and Phishing Attacks

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Introduction

In today's digital landscape, social media platforms play a critical role in how information is shared and consumed. Link previews — the snippets showing images, titles, and descriptions when users paste URLs — have become a key feature to help users verify content before clicking. However, inconsistencies or flaws in how these previews are handled can expose users to deception, phishing, and other cyber threats.

The flaw exists in the LinkedIn mobile application, where the preview displayed for a link where the preview displayed for a link does not update correctly if a malicious URL is injected before publishing. This leads to a mismatch between the displayed preview and the actual link destination, posing significant risks of user deception and abuse.

This repot presents a security issue responsibly discovered and reported by independent cybersecurity researcher Aiman Al-Hadhrami.

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Summary of Security Issue: Native UI Deception via Link Previews

1. User Interaction Is Expected and Routine

The attack only requires a user to click a link in a LinkedIn post — a normal, platform-native action. This clearly qualifies as likely user interaction under LinkedIn’s vulnerability disclosure policy.

2. Native UI Deception, Not External Social Engineering

This vulnerability arises from a design flaw in LinkedIn’s link preview system. When a malicious link is posted, LinkedIn automatically generates a trusted visual preview that can misrepresent the actual destination.

• The deception is embedded within LinkedIn’s own UI.
• No attacker-driven manipulation or off-platform trickery is involved.
• Users are misled by what appears to be a legitimate, LinkedIn-generated preview.

3. Clearly Within In-Scope Policy Criteria

LinkedIn’s policy states:

> “Implementation and design issues that substantially impact LinkedIn members’ data or infrastructure are in scope.”

This vulnerability qualifies because it:

• Abuses LinkedIn’s branding and trust model.
• Enables phishing, credential theft, and potential malware delivery.
• Does so entirely using LinkedIn’s built-in functionality, without exploiting external services or bypassing traditional security controls.

4. Reproducible with a Clear Technical Root Cause

The issue is easily reproducible and is caused by a consistent, identifiable behavior in the link preview generation process.

5. Real-World Impact

This vulnerability has clear potential for large-scale abuse by malicious actors who can craft LinkedIn posts with legitimate-looking previews that direct users to harmful destinations — leveraging LinkedIn’s own trust signals to increase success rates.

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Comparison with Other Platforms

During testing, the same steps were reproduced across several popular messaging and social media platforms, including X (formerly Twitter), Threads, WhatsApp, Signal, and Telegram, I found that only LinkedIn — along with one other unspecified app — retains the initial link preview even after the user replaces the URL before publishing.

In contrast, all other tested platforms correctly update the preview to reflect the new destination URL, thereby preventing any mismatch between the preview and the actual link.

This behavior appears to be platform-specific to LinkedIn, and represents a deviation from the more secure and user-transparent design patterns followed by other major social platforms.

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Platform-Specific Behavior: App vs. Web

"Interestingly, this issue appears to be limited to the LinkedIn mobile application; when performing the same steps via the LinkedIn web interface in a browser, the preview either updates correctly or does not persist once the URL is injected."

This suggests that the flaw may be tied to how the mobile app handles UI state and link preview caching, further supporting its alignment with CWE-451 (UI Misrepresentation) and CWE-345 (Insufficient Verification of Data Authenticity).

Such discrepancies between app and web behavior could increase the risk of exploitation on mobile platforms, where users are less likely to inspect actual URLs before clicking.

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Phishing via Link Preview Mismatch – LinkedIn Job-Seeker Exploitation Scenario

Example:

An attacker creates a LinkedIn post that appears to promote job opportunities from a reputable company, such as:

https://careers.microsoft.com/openings

LinkedIn instantly generates a trusted preview using Microsoft’s branding, job title, and professional imagery — creating strong visual credibility and making the post appear completely legitimate.

Before publishing, the attacker injects a malicious phishing URL into the original link:

https://2u.pw/Semzr

However, LinkedIn does not invalidate or regenerate the preview after the URL injection. As a result, the post still displays a Microsoft-branded preview, but the visible link now leads to a fake login page designed to steal credentials.

Real-World Exploitation Scenario: Job-Seeker in Distress

Imagine a recent graduate or unemployed professional desperately looking for a job.

They come across this LinkedIn post showing an official Microsoft job offer, complete with branding and job descriptions — seemingly shared by a recruiter or hiring manager.

Out of urgency and hope, they:

• Click the link.
• Land on a perfectly cloned login page.
• Enter their LinkedIn credentials — or worse, corporate or email credentials used for job applications.

Result:

• Their account is compromised.
• Their data is harvested.
• They may be locked out of their LinkedIn profile during critical application periods.
• Or worse, the attacker uses the stolen account to spread more phishing through their network — amplifying the attack.

Security and Ethical Implications

This flaw allows attackers to:

• Exploit human trust in professional networks.
• Create targeted phishing attacks under the guise of opportunity.
• Attackers can use LinkedIn ads to target vulnerable job seekers, increasing the success of phishing attacks.
• Harvest credentials, personal information, or sensitive documents (CVs, passports, etc.).
• Cause psychological harm to people already in distress due to unemployment.

The emotional and professional impact can be devastating, especially for vulnerable users. This is not just a visual mismatch — it is a trust-based attack vector that hijacks the core purpose of LinkedIn: connecting people with real opportunities.

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Security Impact

• User Deception: Users may trust the content based on a legitimate-looking preview, unaware that the actual destination is malicious.
• Exploitation via Sponsored Ads: Attackers can use LinkedIn’s paid ads to increase the reach and credibility of malicious posts, targeting specific professional groups and making phishing attacks more effective.
• Legal issue: Using previews based on content from trusted institutions, companies, or organizations may be exploited for phishing or deception and could lead to legal issues.
• Phishing Facilitation: Attackers can present safe-looking previews while linking to phishing sites designed to steal login credentials, banking information, or personal data.
• Sensitive Data Theft: Exploiting this flaw can lead users to fake portals that harvest medical records, financial credentials, personal identification data, and even corporate login information.
• Malware & Spyware Installation: Victims may be redirected to malicious websites that automatically download spyware, keyloggers, ransomware, or other stealth malware.
• Surveillance and Espionage: Malicious actors may use this to target executives, journalists, or government employees, injecting spyware to monitor communications or extract sensitive intelligence.

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Technical Breakdown

• LinkedIn relies on Open Graph tags to fetch preview metadata.
• The preview is generated only when the first URL is pasted.
• When a malicious URL is injected before publishing, LinkedIn does not re-fetch or validate the new link’s metadata.
• This creates a visual mismatch between the displayed preview and the actual link.
• Clicking the visible link in the post, leads to a destination completely unrelated to the image, title, or description shown

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CWE and CAPEC Classifications

• CAPEC-98 – Phishing
• CAPEC-125 – URL Manipulation
• CWE-451 – User Interface Misrepresentation of Critical Information
• CWE-345 – Insufficient Verification of Data Authenticity

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Recommendations for LinkedIn

• Automatically invalidate and regenerate previews when a URL is injected or replaced before publishing.

• Add UI warnings or visual cues to alert users when a link has been modified after preview generation.

• Ensure that the actual destination URL is clearly visible or easily accessible to users before they click.
  

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Responsible Disclosure:

This vulnerability was discovered and responsibly reported by independent cybersecurity researcher Aiman Al-Hadhrami, in accordance with ethical disclosure standards.

It was privately disclosed through LinkedIn's bug bounty program on HackerOne on 2 July 2025 [Report ID: #3235035].

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Research Ethics & Statement:

This research was conducted under the principle of responsible disclosure.

No user data was accessed, and no harm was caused to LinkedIn infrastructure or members.

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Proof of Concept

The vulnerability report, complete with technical documentation and a demonstration video, was submitted to the LinkedIn security team.

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Conclusion

This vulnerability in the LinkedIn mobile application highlights a critical lapse in how link previews are managed — a seemingly minor UI behavior that can be weaponized for serious cyberattacks. By allowing outdated or misleading previews to persist even after the URL has been injected with a new destination, LinkedIn inadvertently opens the door to deception, phishing, and data theft at scale. In an era where trust and authenticity are constantly under threat, such flaws demand urgent attention. It is imperative that LinkedIn addresses this issue promptly by aligning its mobile behavior with industry standards, reinforcing preview validation mechanisms, and empowering users with clearer visibility into the links they engage with. Failure to act not only puts users at risk but also undermines trust in LinkedIn as a secure and professional platform.

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Aiman Al-Hadhrami – Independent Cybersecurity Researcher 

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