CVE-2014-7857 – This vulnerability allows remote attackers to b... (How to Fix)

Q: What is the severity of CVE-2014-7857?

CVE-2014-7857 has a CVSS score of 9.8 (CRITICAL). This vulnerability allows remote attackers to bypass authentication on affected D-Link network storage devices by sending a specific command and setting a cookie. Attackers can gain administrator access without credentials. Users of vulnerable D-Link DNS/DNR series devices are affected.

📋 TL;DR

This vulnerability allows remote attackers to bypass authentication on affected D-Link network storage devices by sending a specific command and setting a cookie. Attackers can gain administrator access without credentials. Users of vulnerable D-Link DNS/DNR series devices are affected.

💻 Affected Systems

Products:

D-Link DNS-320L
D-Link DNS-327L
D-Link DNR-326
D-Link DNS-320B
D-Link DNS-345
D-Link DNS-325
D-Link DNS-322L

Versions: DNS-320L before 1.04b12, DNS-327L before 1.03b04 Build0119, DNR-326 before 1.40b03, DNS-320B before 1.02b01, DNS-345 before 1.03b06, DNS-325 before 1.05b03, DNS-322L before 2.00b07

Operating Systems: Embedded Linux-based firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations are vulnerable. The web management interface must be accessible for exploitation.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of the network storage device, allowing attackers to access, modify, or delete all stored data, install malware, or use the device as a pivot point into the network.

🟠

Likely Case

Unauthorized access to sensitive files stored on the device, potential data theft or ransomware deployment, and device configuration changes.

🟢

If Mitigated

Limited impact if device is isolated from internet and internal networks, with strict access controls and monitoring in place.

🌐 Internet-Facing: HIGH - The exploit is unauthenticated and can be executed remotely over HTTP, making internet-facing devices extremely vulnerable.

🏢 Internal Only: HIGH - Even internally, the vulnerability allows any network user to gain administrative access without credentials.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: CONFIRMED

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploit code is publicly available and requires minimal technical skill to execute. The attack involves a simple HTTP request with specific parameters.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: DNS-320L 1.04b12, DNS-327L 1.03b04 Build0119, DNR-326 1.40b03, DNS-320B 1.02b01, DNS-345 1.03b06, DNS-325 1.05b03, DNS-322L 2.00b07

Vendor Advisory: http://www.search-lab.hu/media/D-Link_Security_advisory_3_0_public.pdf

Restart Required: Yes

Instructions:

1. Download the latest firmware from D-Link support site for your specific model. 2. Log into the web interface (if possible). 3. Navigate to Management > Firmware Update. 4. Upload the firmware file. 5. Wait for the device to reboot automatically.

🔧 Temporary Workarounds

Block Web Interface Access

linux

Restrict access to the device's web management interface using firewall rules.

iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP

Disable Remote Management

all

Turn off remote management feature in device settings if not needed.

🧯 If You Can't Patch

Isolate the device on a separate VLAN with strict access controls.
Implement network monitoring for suspicious authentication bypass attempts to the device's IP.

🔍 How to Verify

Check if Vulnerable:

Check current firmware version in web interface under System > Firmware Information. Compare against patched versions listed above.

Check Version:

curl -s http://device-ip/fw_version.txt or check web interface

Verify Fix Applied:

After updating, verify the firmware version matches patched versions. Test authentication by attempting to access admin functions without proper credentials.

📡 Detection & Monitoring

Log Indicators:

HTTP requests containing 'cmd=cgi_set_wto' parameter
Successful admin logins from unexpected IP addresses
Failed authentication attempts followed by successful access

Network Indicators:

HTTP POST requests to device IP with suspicious parameters
Unusual traffic patterns to/from the storage device

SIEM Query:

source="device-ip" AND (http_uri="*cmd=cgi_set_wto*" OR user="admin" AND auth_result="success" FROM new_ip)

📊 Metadata

CVE ID: CVE-2014-7857

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-287

Published: August 25, 2017

Last Updated: April 20, 2025

🔗 References

http://packetstormsecurity.com/files/132075/D-Link-Bypass-Buffer-Overflow.html Third Party Advisory,VDB Entry
http://seclists.org/fulldisclosure/2015/May/125 Mailing List,Third Party Advisory,VDB Entry
http://www.search-lab.hu/media/D-Link_Security_advisory_3_0_public.pdf Technical Description
http://www.securityfocus.com/archive/1/535626/100/200/threaded
http://www.securityfocus.com/bid/74880 Third Party Advisory,VDB Entry
http://packetstormsecurity.com/files/132075/D-Link-Bypass-Buffer-Overflow.html Third Party Advisory,VDB Entry
http://seclists.org/fulldisclosure/2015/May/125 Mailing List,Third Party Advisory,VDB Entry
http://www.search-lab.hu/media/D-Link_Security_advisory_3_0_public.pdf Technical Description
http://www.securityfocus.com/archive/1/535626/100/200/threaded
http://www.securityfocus.com/bid/74880 Third Party Advisory,VDB Entry

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