CVE-2021-23853 – This vulnerability in Bosch IP cameras allows a... (How to Fix)

Q: What is the severity of CVE-2021-23853?

CVE-2021-23853 has a CVSS score of 8.3 (HIGH). This vulnerability in Bosch IP cameras allows attackers to inject arbitrary HTTP headers through specially crafted URLs due to improper input validation. Attackers could manipulate HTTP responses to conduct various attacks. All users of affected Bosch IP camera models are at risk.

📋 TL;DR

This vulnerability in Bosch IP cameras allows attackers to inject arbitrary HTTP headers through specially crafted URLs due to improper input validation. Attackers could manipulate HTTP responses to conduct various attacks. All users of affected Bosch IP camera models are at risk.

💻 Affected Systems

Products:

Bosch IP cameras

Versions: Specific versions not detailed in advisory; check vendor advisory for exact affected versions

Operating Systems: Embedded camera firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations of affected cameras are vulnerable. Requires HTTP access to camera interface.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise allowing remote code execution, camera control takeover, or network pivoting to internal systems.

🟠

Likely Case

HTTP response manipulation leading to client-side attacks like XSS, session hijacking, or credential theft against camera administrators.

🟢

If Mitigated

Limited impact with proper network segmentation and access controls preventing external exploitation.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Crafted URL exploitation suggests low complexity. No public exploit code identified.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check vendor advisory for specific firmware versions

Vendor Advisory: https://psirt.bosch.com/security-advisories/bosch-sa-478243-bt.html

Restart Required: Yes

Instructions:

1. Access Bosch PSIRT advisory. 2. Identify affected camera models. 3. Download latest firmware from Bosch support portal. 4. Upload firmware via camera web interface. 5. Reboot camera after update.

🔧 Temporary Workarounds

Network segmentation

all

Isolate cameras on separate VLAN with strict firewall rules

Access restriction

linux

Restrict HTTP access to camera interfaces using firewall rules

iptables -A INPUT -p tcp --dport 80 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

🧯 If You Can't Patch

Implement strict network segmentation to isolate cameras from untrusted networks
Deploy web application firewall (WAF) rules to block HTTP header injection patterns

🔍 How to Verify

Check if Vulnerable:

Check camera firmware version against vendor advisory. Test with controlled HTTP header injection attempts.

Check Version:

Check camera web interface → System → Information for firmware version

Verify Fix Applied:

Verify firmware version matches patched version from advisory. Test HTTP header injection attempts fail.

📡 Detection & Monitoring

Log Indicators:

Unusual HTTP requests with crafted URLs
Multiple failed authentication attempts following header manipulation

Network Indicators:

HTTP requests with unusual header patterns
Traffic to camera web interface from unexpected sources

SIEM Query:

source="camera_logs" AND (url="*%0D%0A*" OR url="*%0A*" OR url="*%0D*")

📊 Metadata

CVE ID: CVE-2021-23853

CVSS v3 Score: 8.3 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

CWE: CWE-20

Published: June 9, 2021

Last Updated: November 21, 2024

🔗 References

https://psirt.bosch.com/security-advisories/bosch-sa-478243-bt.html Vendor Advisory
https://psirt.bosch.com/security-advisories/bosch-sa-478243-bt.html Vendor Advisory

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