CVE-2022-29588: Konicaminolta Bizhub 226i Password Exposure

CVE-2022-29588 Overview

CVE-2022-29588 is a cleartext password storage vulnerability affecting Konica Minolta bizhub multifunction printer (MFP) devices with firmware versions prior to 2022-04-14. The vulnerability exists because sensitive credential files, specifically /var/log/nginx/html/ADMINPASS and /etc/shadow, store passwords in cleartext rather than using secure hashing mechanisms. This weakness allows an attacker who gains access to the device's file system to retrieve administrative credentials without needing to crack password hashes.

Critical Impact

Attackers who exploit this vulnerability can obtain administrative credentials in cleartext, potentially leading to complete device compromise, lateral movement within the network, and unauthorized access to sensitive documents processed by the MFP devices.

Affected Products

• Konica Minolta bizhub 226i, 227, 246i, 287, 306i, 308, 308e, 367, 368, 368e firmware
• Konica Minolta bizhub 4052, 458, 458e, 4752, 558, 558e, 658e, 758, 808, 958 firmware
• Konica Minolta bizhub C-series (C227, C250i, C258, C287, C300i, C308, C3300i, C3320i, C3350i, C3351, C360i, C368, C3851, C3851fs, C4000i, C4050i, C450i, C458, C550i, C558, C650i, C658, C659, C759, Pro958) firmware

Discovery Timeline

• May 16, 2022 - CVE-2022-29588 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-29588

Vulnerability Analysis

This vulnerability is classified as CWE-522 (Insufficiently Protected Credentials). The affected Konica Minolta bizhub MFP devices store administrative passwords and system credentials in cleartext within two critical files on the device's file system. The /var/log/nginx/html/ADMINPASS file contains the administrative password for the device's web interface, while the /etc/shadow file—which traditionally should contain hashed passwords on Unix-like systems—also stores credentials in cleartext format.

The exploitation of this vulnerability requires an attacker to first gain access to the device's file system. This could be achieved through various means, including exploiting other vulnerabilities in the MFP device, gaining physical access, or leveraging the sandbox escape vulnerability documented in related research from SEC Consult Vulnerability Lab.

Root Cause

The root cause of this vulnerability is improper credential management within the firmware of affected Konica Minolta bizhub MFP devices. Instead of implementing industry-standard password hashing algorithms (such as bcrypt, scrypt, or SHA-512 with proper salting), the device stores credentials in plaintext format. This represents a fundamental security design flaw that violates basic secure coding practices for credential storage.

Attack Vector

The attack vector for this vulnerability is network-based, requiring the attacker to first establish access to the MFP device's file system. Once an attacker gains file system access—whether through a companion vulnerability, compromised service, or physical access to the device—they can directly read the cleartext passwords from the affected files.

The attack scenario typically involves:

1. Gaining initial access to the MFP device through network exploitation or physical access
2. Navigating to /var/log/nginx/html/ADMINPASS or /etc/shadow
3. Reading the cleartext administrative credentials
4. Using the obtained credentials to authenticate as an administrator
5. Potentially pivoting to other network resources using harvested credentials

According to the Packet Storm Security Report, this vulnerability was discovered alongside a terminal sandbox escape, which provides a practical path for attackers to access these sensitive files.

Detection Methods for CVE-2022-29588

Indicators of Compromise

• Unusual file access attempts targeting /var/log/nginx/html/ADMINPASS or /etc/shadow on MFP devices
• Unauthorized administrative logins to bizhub MFP web interfaces from unexpected IP addresses
• Evidence of sandbox escape or shell access attempts on affected devices
• Network traffic indicating credential harvesting or exfiltration from MFP devices

Detection Strategies

• Monitor network traffic to and from MFP devices for unusual patterns, including unexpected SSH or telnet connections
• Implement file integrity monitoring on critical MFP configuration and log directories where possible
• Review authentication logs on the MFP devices for failed or successful logins from untrusted sources
• Deploy network segmentation to isolate MFP devices and monitor inter-segment traffic

Monitoring Recommendations

• Enable logging on bizhub MFP devices and forward logs to a centralized SIEM solution
• Monitor for lateral movement attempts originating from MFP device IP addresses
• Implement alerting for any administrative access to MFP devices outside of maintenance windows
• Conduct periodic security assessments of MFP devices to identify firmware versions and potential exposures

How to Mitigate CVE-2022-29588

Immediate Actions Required

• Inventory all Konica Minolta bizhub MFP devices in your environment and identify firmware versions
• Apply firmware updates released after 2022-04-14 to all affected devices immediately
• Change administrative passwords on all affected devices after patching
• Implement network segmentation to restrict access to MFP devices from untrusted networks

Patch Information

Konica Minolta addressed this vulnerability in firmware updates released after April 14, 2022. Organizations should contact Konica Minolta support or visit the SEC Consult Vulnerability Lab for detailed information about affected firmware versions and available patches. Ensure all affected bizhub models are updated to the latest firmware version that addresses this cleartext password storage issue.

Workarounds

• Restrict network access to MFP devices using firewall rules or VLANs to limit exposure
• Disable unnecessary services on the MFP devices to reduce attack surface
• Implement strong network access controls requiring authentication before accessing MFP device management interfaces
• Monitor and audit access to MFP devices until firmware patches can be applied

# Example network segmentation using iptables (on a gateway device)
# Restrict access to MFP management ports from untrusted networks
iptables -A FORWARD -s 10.0.0.0/8 -d 192.168.100.0/24 -p tcp --dport 80 -j DROP
iptables -A FORWARD -s 10.0.0.0/8 -d 192.168.100.0/24 -p tcp --dport 443 -j DROP
iptables -A FORWARD -s 10.0.0.0/8 -d 192.168.100.0/24 -p tcp --dport 22 -j DROP
# Allow only trusted management network
iptables -A FORWARD -s 172.16.10.0/24 -d 192.168.100.0/24 -p tcp --dport 443 -j ACCEPT