CVE-2020-26146: Samsung Galaxy I9305 Disclosure Flaw

CVE-2020-26146 Overview

CVE-2020-26146 is a Wi-Fi protocol implementation vulnerability affecting the WPA, WPA2, and WPA3 implementations in various devices. The flaw allows these implementations to reassemble fragments with non-consecutive packet numbers, enabling an adversary to exfiltrate selected fragments from encrypted wireless communications. This vulnerability is part of the broader FragAttacks (Fragmentation and Aggregation Attacks) family of Wi-Fi vulnerabilities that affect the fundamental design of the 802.11 standard.

Critical Impact

Attackers within adjacent network range can abuse the improper fragment reassembly to exfiltrate selected encrypted fragments, potentially exposing sensitive data transmitted over Wi-Fi networks using WEP, CCMP, or GCMP data-confidentiality protocols.

Affected Products

• Samsung Galaxy S3 i9305 (firmware 4.4.4)
• Arista C-Series and O-Series Access Points (C-250, C-260, C-230, C-235, C-200, C-120, C-130, C-100, C-110, O-105, O-90, C-75, C-65)
• Arista W-Series Wireless Access Points (W-118, W-68)
• Siemens SCALANCE W700 IEEE 802.11n
• Siemens SCALANCE W1700 IEEE 802.11ac
• Siemens SCALANCE W1750D

Discovery Timeline

• May 11, 2021 - CVE-2020-26146 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-26146

Vulnerability Analysis

This vulnerability exists in the Wi-Fi fragment reassembly process across multiple protocol implementations. When wireless devices communicate using WPA, WPA2, or WPA3, large frames can be split into smaller fragments for transmission. The receiving device is responsible for reassembling these fragments in the correct order before processing the complete frame.

The affected implementations fail to properly validate that reassembled fragments maintain consecutive packet numbers. This improper input validation (CWE-20) allows an attacker to inject or manipulate fragments within the reassembly queue, potentially leading to data exfiltration. The vulnerability requires the attacker to be within the adjacent network range of the target device and is exploitable when WEP, CCMP, or GCMP encryption is in use. Notably, WEP is fundamentally vulnerable to this attack by design due to its weak cryptographic properties.

Root Cause

The root cause of CVE-2020-26146 is improper input validation in the Wi-Fi frame fragment reassembly logic. The vulnerable implementations do not enforce strict sequential ordering of fragment packet numbers during the reassembly process. This missing validation check allows an adversary to inject fragments with arbitrary sequence numbers into an ongoing fragmented transmission, which the device will incorrectly accept and process as legitimate traffic.

Attack Vector

The attack requires the adversary to be within the adjacent network range (wireless range) of the target device. The attacker must intercept fragmented frames being transmitted by another device on the network and inject malicious fragments or manipulate the reassembly process to exfiltrate data.

The attack scenario involves:

1. Positioning within wireless range of the target network
2. Monitoring for fragmented frame transmissions between devices
3. Injecting crafted fragments with non-consecutive packet numbers
4. Exploiting the improper reassembly to extract selected encrypted fragments

Since this is a protocol-level implementation flaw, exploitation does not require user interaction. The attack complexity is elevated due to the need for precise timing and proximity requirements. Technical details and testing tools are available through the FragAttacks Official Website and the GitHub FragAttacks Summary.

Detection Methods for CVE-2020-26146

Indicators of Compromise

• Unusual fragmented frame activity patterns in wireless network traffic logs
• Detection of fragments with non-sequential packet numbers in wireless frame captures
• Anomalous reassembly behavior observed in wireless intrusion detection systems

Detection Strategies

• Deploy wireless intrusion detection/prevention systems (WIDS/WIPS) capable of analyzing 802.11 frame fragmentation patterns
• Monitor for unusual frame injection attempts or replay attacks in proximity to access points
• Implement network traffic analysis to detect potential fragment manipulation attacks
• Review device firmware versions against vendor security advisories to identify vulnerable deployments

Monitoring Recommendations

• Enable detailed logging on wireless access points and controllers to capture fragment-level traffic data
• Implement continuous monitoring of wireless network traffic for anomalous fragmentation patterns
• Deploy SentinelOne Singularity platform on endpoints connected to wireless networks to detect post-exploitation activities
• Establish baseline wireless traffic patterns to identify deviations that may indicate active exploitation

How to Mitigate CVE-2020-26146

Immediate Actions Required

• Identify all affected devices in your environment by reviewing the vendor advisories from Samsung, Arista, and Siemens
• Apply firmware updates from device manufacturers as they become available
• Disable WEP encryption immediately if still in use, as it is inherently vulnerable to this attack
• Ensure WPA3 with Protected Management Frames (PMF) is enabled where supported

Patch Information

Vendors have released security advisories and firmware updates to address this vulnerability. Organizations should consult the following resources for device-specific patch information:

• Siemens Security Advisory Document for SCALANCE W700/W1700 series devices
• Arista Security Advisory Notice for C-Series, O-Series, and W-Series access points
• Cisco Security Advisory for related Cisco products
• Additional technical details available via the Openwall Security Mailing List Post

Workarounds

• If patching is not immediately possible, implement network segmentation to limit exposure of vulnerable wireless devices
• Disable frame fragmentation at the access point level where operationally feasible
• Use VPN encryption for sensitive communications over wireless networks to add an additional layer of protection
• Consider replacing end-of-life devices that will not receive firmware updates (such as Samsung Galaxy S3 i9305)

# Example: Verify firmware version on Linux-based wireless systems
# Check wireless interface driver and firmware versions
iwconfig wlan0
ethtool -i wlan0

# Review wireless driver module information
modinfo <wireless_driver_name>

# Check system logs for wireless-related warnings
dmesg | grep -i "wifi\|wlan\|wireless"