CVE-2013-7041

What it actually does

pam_userdb performs case-insensitive comparison of password hashes, reducing the effective search space for brute-force attacks against stored credentials.

Why it matters to the business

Older deployments using affected PAM modules face elevated risk of credential compromise through automated guessing, potentially leading to unauthorized system access in environments that have not applied long-available updates.

How an attack unfolds

An attacker obtains or targets a system using pam_userdb for authentication, captures password hash material, and performs offline brute-force attempts that succeed more readily because the comparison ignores case, allowing fewer guesses to cover common password variants.

How to fix it

Upgrade samba packages on Debian 10-13 to the fixed versions 3.0.23d-5 or later; replace pam_userdb usage with case-sensitive alternatives where possible and enforce strong password policies.

How to confirm the fix worked

Confirm package versions match or exceed the listed fixed releases, review PAM configuration files for continued use of pam_userdb, and test authentication behavior to ensure case-sensitive comparisons are enforced.

Typical attack path

1. Identify hosts or services relying on pam_userdb for authentication
2. Obtain password hashes through network access, log exposure, or local file read
3. Launch offline brute-force or dictionary attack leveraging case-insensitive hash comparison
4. Use recovered credentials to authenticate to the target system or pivot

How to detect it

Review historical authentication logs and PAM configuration files for references to pam_userdb; look for repeated failed login attempts originating from the same sources over extended periods.

What your security team should do

• Apply the specified package updates immediately on all affected Debian systems
• Audit PAM stacks for pam_userdb usage and migrate away from the module
• Monitor authentication logs for anomalous login patterns
• Enforce password complexity requirements to offset residual guessing risk