This vulnerability allows attackers to execute arbitrary code in the context of a victim user. Specifically, PsySH, a runtime developer console for PHP, has a flaw that can lead to local privilege escalation if a victim runs it from a directory writable by the attacker.
The vulnerability affects versions prior to 0.11.23 and 0.12.19, with the CVSS score measured at 6.7, indicating a medium severity level. Organizations should be aware of the risk posed by this vulnerability, especially in scenarios where PsySH is run with elevated privileges.
In practical terms, if an attacker can write to a directory that a privileged user utilizes as their Current Working Directory (CWD) when launching PsySH, they can trigger arbitrary code execution. This risk escalates significantly when the privileged user is running PsySH as the root user, potentially granting the attacker full control over the system.
Given the nature of this vulnerability, it is imperative that organizations address this issue promptly. Users should prioritize patching to mitigate the risk of exploitation. The patches released in versions 0.11.23 and 0.12.19 effectively resolve the vulnerability.
Vulnerability Details
According to the official CVE description, this vulnerability is categorized under CWE-427 (Uncontrolled Search Path Element). It arises from PsySH's behavior of auto-loading and executing a `.psysh.php` file from the Current Working Directory on startup. If a privileged user starts PsySH from an attacker-writable directory containing a malicious `.psysh.php`, arbitrary code can be executed with that user's permissions.
The attack vector is local, requiring the attacker to have write access to the directory. The complexity of exploiting this vulnerability is high, as it requires user interaction to trigger the execution of the payload. The confidentiality, integrity, and availability impacts are all rated as high, indicating a significant risk to affected systems.
PsySH versions 0.11.23 and 0.12.19 have mitigated this issue, and it is crucial for organizations to update to these versions to safeguard against potential exploitation.
Technical Analysis
The root cause of this vulnerability lies in how PsySH handles the CWD during its startup process. By default, it automatically loads a specific configuration file that can be manipulated by an attacker if they have write permissions in the directory. This leads to arbitrary code execution in the victim's context, particularly when the victim is executing PsySH with elevated privileges.
The attack vector is local, meaning the attacker must have physical or remote access to the machine where PsySH is installed. The attack complexity is deemed high due to the requirement for user interaction, as the victim must run PsySH from the compromised directory. Privileges required for the attack are low, as any user with write access to the directory can potentially exploit this vulnerability.
In terms of impact, the confidentiality, integrity, and availability of the system can all be significantly compromised, as the attacker may execute arbitrary commands with the privileges of the victim user.
Risk & Impact Analysis
The real-world risk associated with this vulnerability is substantial, particularly in environments where PsySH is used as part of development or debugging processes. Organizations employing PsySH in production or with elevated user privileges should be particularly vigilant.
The blast radius potential is significant, as any organization that uses PsySH, especially in conjunction with frameworks like Laravel (which utilizes PsySH), can inherit this risk. If an attacker can leverage this vulnerability, they may gain unauthorized access to sensitive data or critical system functions, leading to broader security breaches.
Given the CVSS score of 6.7, organizations should address this vulnerability in their priority patch cycle, ensuring that all instances of PsySH are updated to the latest versions to mitigate the associated risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
PsySH versions prior to 0.11.23 and from 0.12.0 to 0.12.19 are affected by this vulnerability. Organizations should ensure they are running versions that have patched this issue.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to PsySH versions 0.11.23 or 0.12.19. If upgrading is not immediately possible, ensure that the working directories used by privileged users are not writable by attackers.
For further guidance, organizations can consider implementing penetration testing to identify similar weaknesses in their systems.
Detection Guidance
Organizations should monitor logs for indications of unauthorized file access or modifications within directories used for PsySH. Any unexpected execution of `.psysh.php` files should be investigated as potential indicators of compromise.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability lies in its demonstration of how misconfigurations can lead to severe security risks. It highlights the necessity for developers and system administrators to maintain strict control over the directories in which runtime tools operate.
Security teams should learn from this incident to enforce stricter configurations and regularly audit permissions on critical directories. For those interested in improving their security posture, exploring resources on penetration testing methodologies and vulnerability management programs can provide valuable insights.
Moreover, organizations should consider adopting practices from the API penetration testing guide to uncover vulnerabilities that might not be immediately apparent.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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