CVE-2020-26145: Samsung Galaxy I9305 Firmware RCE Flaw

CVE-2020-26145 Overview

CVE-2020-26145 is an improper input validation vulnerability affecting WiFi implementations across multiple devices, including Samsung Galaxy S3 i9305 and various Siemens industrial networking equipment. The vulnerability exists in the WEP, WPA, WPA2, and WPA3 implementations, which incorrectly accept second (or subsequent) broadcast fragments even when sent in plaintext and process them as full unfragmented frames. This flaw allows an adversary within adjacent network range to inject arbitrary network packets independent of the network configuration.

This vulnerability is part of the FragAttacks (fragmentation and aggregation attacks) family of WiFi security flaws that affect a wide range of WiFi devices and implementations.

Critical Impact

An attacker within WiFi range can inject arbitrary network packets by exploiting improper handling of plaintext broadcast fragments, potentially compromising network integrity and enabling man-in-the-middle scenarios.

Affected Products

• Samsung Galaxy S3 i9305 with firmware version 4.4.4
• Siemens SCALANCE industrial wireless devices (multiple models including 6GK5763 and 6GK5766 series)
• Siemens RUGGEDCOM industrial networking equipment

Discovery Timeline

• May 11, 2021 - CVE-2020-26145 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-26145

Vulnerability Analysis

This vulnerability stems from a fundamental flaw in how affected WiFi implementations handle frame fragmentation. The 802.11 WiFi standard allows large frames to be split into smaller fragments for transmission. These fragments are then reassembled by the receiver. The vulnerability occurs because the affected implementations fail to properly validate whether subsequent broadcast fragments are encrypted, accepting plaintext fragments and processing them as legitimate unfragmented frames.

The attack exploits the fragment cache mechanism in WiFi receivers. When a device receives the first fragment of a broadcast frame, it stores this in a cache awaiting subsequent fragments. The vulnerability allows an attacker to inject plaintext fragments that the receiver incorrectly accepts and processes, even in networks using WEP, WPA, WPA2, or WPA3 encryption.

Root Cause

The root cause is classified as CWE-20 (Improper Input Validation). The WiFi implementation fails to properly validate that subsequent broadcast fragments maintain the same encryption state as the initial fragment. Specifically, the receiver does not verify that incoming fragments are encrypted when the network configuration requires encryption, allowing plaintext fragments to be accepted and processed as valid data.

Attack Vector

The attack requires the adversary to be within adjacent network range (WiFi proximity) of the target device. The attacker does not need authentication to the network or any user interaction to exploit this vulnerability. The attack proceeds as follows:

1. The attacker monitors broadcast traffic on the target WiFi network
2. Upon observing an encrypted broadcast frame or initiating one through traffic manipulation, the attacker injects a crafted plaintext fragment claiming to be a subsequent fragment
3. The vulnerable receiver accepts this plaintext fragment due to improper validation
4. The receiver processes the injected content as legitimate network data

The vulnerability enables packet injection attacks that can be used for various malicious purposes, including DNS spoofing, ARP poisoning, or injecting malicious content into network communications. Since broadcast frames reach all devices on the network segment, this attack can potentially affect multiple devices simultaneously.

For detailed technical information about this FragAttacks vulnerability, refer to the FragAttacks Official Website and the GitHub FragAttacks Summary.

Detection Methods for CVE-2020-26145

Indicators of Compromise

• Unexpected or malformed broadcast frames appearing in WiFi traffic captures
• Anomalous network behavior such as DNS resolution failures or unexpected redirects
• Wireless IDS/IPS alerts indicating fragment injection or reassembly anomalies
• Unusual ARP traffic patterns suggesting ARP spoofing attempts

Detection Strategies

• Deploy wireless intrusion detection systems (WIDS) configured to detect fragment-based attacks
• Monitor for broadcast frames with inconsistent encryption states between fragments
• Implement network traffic analysis to identify anomalous packet injection patterns
• Use WiFi security auditing tools designed to detect FragAttacks vulnerabilities

Monitoring Recommendations

• Enable verbose logging on wireless access points and controllers
• Implement continuous wireless network monitoring with alerting for anomalous frame patterns
• Deploy SentinelOne Singularity for endpoint visibility to detect post-exploitation activity
• Conduct regular security assessments of WiFi infrastructure using FragAttacks testing tools

How to Mitigate CVE-2020-26145

Immediate Actions Required

• Apply firmware updates from device manufacturers that address FragAttacks vulnerabilities
• Ensure all WiFi traffic uses HTTPS/TLS to mitigate the impact of potential packet injection
• Consider network segmentation to limit the blast radius of potential attacks
• Audit all affected Siemens industrial devices and prioritize patching in critical environments

Patch Information

Vendors have released firmware updates addressing this vulnerability. For Siemens industrial equipment, refer to the Siemens Security Advisory SSA-913875 for specific patch information and affected product versions. Samsung Galaxy S3 i9305 users should note that this device is end-of-life and may not receive official patches.

Organizations should:

• Review the Siemens security advisory for applicable firmware versions
• Contact Samsung or carrier support regarding updates for affected mobile devices
• Implement compensating controls for devices that cannot be patched

Workarounds

• Use end-to-end encryption (HTTPS, VPN) for all network communications to protect against injected content
• Disable frame aggregation where possible (may impact performance)
• Implement strict network access controls and monitoring on affected network segments
• Replace end-of-life devices that cannot receive security updates with supported alternatives

# Example: Monitor for FragAttacks indicators using tcpdump
# Capture and analyze WiFi traffic for anomalous fragment patterns
tcpdump -i wlan0 -w capture.pcap 'type data subtype data-fragmentation'

# Verify firmware version on Siemens devices (via web interface or CLI)
# Ensure firmware meets minimum patched version per SSA-913875