CVE-2023-52723

Executive Summary

CVE-2023-52723 is a cleartext password exposure vulnerability in KDE libksieve, a library for managing Sieve email filtering scripts. The flaw exists in the kmanagesieve/session.cpp file, where a coding error causes the password value to be accidentally assigned to a username variable, resulting in the cleartext password being written to server logs. This vulnerability affects versions prior to 23.03.80. The CVSS score is 0.0 due to incomplete NVD data, but the actual risk is significant for local information disclosure. No public exploit code or PoC is available, and the EPSS score is 0.0%, indicating low exploitation activity.

Supply Chain & Package Security

This vulnerability is in the KDE libksieve library, which is part of the KDE PIM (Personal Information Management) suite. It is distributed via KDE's repositories and Linux package managers. Users should verify they are using version 23.03.80 or later to mitigate the risk.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (AV:L) – The attacker must have local access to the system logs.
• Attack Complexity (AC): Low (AC:L) – No special conditions required.
• Privileges Required (PR): Low (PR:L) – Attacker needs access to the log files.
• User Interaction (UI): None (UI:N) – No user action needed.
• Scope (S): Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – Cleartext password is exposed.
• Integrity (I): None (I:N) – No data modification.
• Availability (A): None (A:N) – No impact on availability.

Threat Level: Medium (Local Information Disclosure)

Deep Dive & Mechanics

The vulnerability is located in kmanagesieve/session.cpp. The code incorrectly assigns the password value to a variable intended for the username. This causes the password to be logged in cleartext when the session is established. The root cause is a simple variable name swap or copy-paste error in the source code.

Affected Code Path:

1. User configures a Sieve server connection with a username and password.
2. The session.cpp code attempts to log the username for debugging purposes.
3. Due to the bug, the password is written to the log instead of the username.
4. An attacker with read access to the server logs can retrieve the cleartext password.

Vulnerable vs. Patched Code

Vulnerable Code (before 23.03.80):

// kmanagesieve/session.cpp
void Session::logConnectionDetails() {
    // Bug: password assigned to username variable
    QString username = m_password; // Incorrect
    qDebug() << "Connecting with username:" << username;
}

Patched Code (23.03.80 and later):

// kmanagesieve/session.cpp
void Session::logConnectionDetails() {
    // Fix: use correct variable
    QString username = m_username; // Correct
    qDebug() << "Connecting with username:" << username;
}

Exploitation & Lab Setup

Red Team

No public exploit code exists. To demonstrate the vulnerability:

1. Set up a KDE environment with libksieve < 23.03.80.
2. Configure a Sieve server connection with a test password.
3. Trigger the connection and check the application logs (e.g., ~/.local/share/kdebug.log or systemd journal).
4. Observe the cleartext password in the log output.

Example log entry:

Connecting with username: MySecretPassword123

Blue Team

• Monitor logs for unexpected cleartext strings that resemble passwords.
• Use file integrity monitoring to detect changes to log files.
• Restrict access to log files to authorized personnel only.

Indicators of Compromise (IOCs)

• Log Pattern: Connecting with username: followed by a string that is not a valid username (e.g., contains special characters or looks like a password).
• File Paths: ~/.local/share/kdebug.log, /var/log/syslog, or systemd journal entries containing the above pattern.
• Process: kmanagesieve or any KDE PIM process writing to logs.

Detection Engineering

YARA Rule

rule CVE_2023_52723_LogExposure {
    meta:
        description = "Detects cleartext password exposure in KDE libksieve logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-52723"
    strings:
        $log_pattern = "Connecting with username:"
    condition:
        $log_pattern
}

Sigma Rule

title: Cleartext Password in KDE libksieve Logs
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects cleartext password exposure from CVE-2023-52723
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: kde
detection:
    selection:
        EventID: 0
        Message|contains: "Connecting with username:"
    condition: selection
falsepositives:
    - Legitimate username logging (if patched)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2023-52723 KDE libksieve Cleartext Password in Logs"; content:"Connecting with username:"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Upgrade: Update to KDE libksieve version 23.03.80 or later.
2. Log Rotation: Implement log rotation and retention policies to limit exposure.
3. Access Control: Restrict read access to log files to only necessary personnel.
4. Audit: Review existing logs for any exposed credentials and rotate affected passwords.
5. Monitoring: Deploy the provided detection rules to identify any exploitation attempts.

Valters IT Signature

This report was generated by Valters IT DevSecOps Intelligence. For questions, contact security@valters-it.com.