CVE-2025-1057

Executive Summary

CVE-2025-1057 is a compatibility regression in Keylime, a remote attestation solution. The vulnerability arises from a strict type-checking change introduced in version 7.12.0, which causes the registrar to reject database entries created by earlier versions (e.g., 7.11.0). Specifically, older versions store agent registration data as bytes, while the updated registrar expects str. This mismatch leads to an exception during agent registration, effectively breaking the attestation workflow. The CVSS score is 0.0 due to incomplete data, but the actual impact is a denial of service for agent registration. No public exploit or patch exists at this time.

Supply Chain & Package Security

Keylime is a Python-based project distributed via PyPI. The vulnerability is a code-level regression, not a dependency issue. However, organizations using Keylime should verify their deployment version and ensure no automatic updates to 7.12.0 occur without testing.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The registrar is typically network-accessible.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – Unauthenticated agents can trigger the issue.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Only the registrar component is affected.
• Confidentiality (C): None (N) – No data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): Low (L) – Agent registration fails, but existing agents may continue.

Threat Level: Medium (Availability impact only, but critical for attestation workflows).

Deep Dive & Mechanics

The vulnerability is a type confusion (CWE-704) in the Keylime registrar’s database handling. In version 7.12.0, the codebase introduced strict type checking for agent registration data, expecting str fields. However, earlier versions (e.g., 7.11.0) stored these fields as bytes (e.g., b'agent_id'). When the registrar attempts to read or process these old entries, it raises a TypeError or ValueError, causing the agent registration to fail.

Root Cause: The change was likely intended to improve data integrity but broke backward compatibility. The fix would involve either converting bytes to str on read or reverting the type enforcement.

Attack Vector: An attacker with network access to the registrar can send a registration request that triggers the exception, but the primary impact is on legitimate agents that were registered before the upgrade.

Vulnerable vs. Patched Code

Vulnerable Code (7.12.0):

# registrar.py (simplified)
def process_registration(data):
    agent_id = data['agent_id']  # Expects str, but old data is bytes
    if not isinstance(agent_id, str):
        raise TypeError("agent_id must be str")
    # ... rest of processing

Patched Code (suggested fix):

# registrar.py (patched)
def process_registration(data):
    agent_id = data['agent_id']
    if isinstance(agent_id, bytes):
        agent_id = agent_id.decode('utf-8')  # Convert bytes to str
    # ... rest of processing

Exploitation & Lab Setup

Red Team

No public exploit exists. To simulate the issue:

1. Deploy Keylime 7.11.0 and register an agent.
2. Upgrade to 7.12.0.
3. Attempt to re-register the same agent – the registrar will throw an exception.

Proof of Concept (Python):

# Simulate the type mismatch
old_data = {'agent_id': b'legacy_agent'}
# In 7.12.0, this would fail:
try:
    agent_id = old_data['agent_id']
    if not isinstance(agent_id, str):
        raise TypeError("agent_id must be str")
except TypeError as e:
    print(f"Registration failed: {e}")

Blue Team

• Monitor registrar logs for TypeError or ValueError related to agent registration.
• Check for agents that fail to register after a Keylime upgrade.
• Implement a temporary workaround by patching the registrar to handle bytes gracefully.

Indicators of Compromise (IOCs)

• Log Entry: TypeError: agent_id must be str in Keylime registrar logs.
• Failed Registration: Agents with IDs starting with b' (byte string representation) in logs.
• Database Anomaly: Entries in the registrar database where agent_id is stored as bytes instead of str.

Detection Engineering

YARA Rule

rule CVE_2025_1057_Keylime_TypeError {
    meta:
        description = "Detects Keylime registrar logs indicating type mismatch for agent_id"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-1057"
    strings:
        $type_error = "TypeError: agent_id must be str" nocase
        $value_error = "ValueError: agent_id" nocase
    condition:
        any of them
}

Sigma Rule

title: Keylime Registrar Type Mismatch
id: cve-2025-1057
status: experimental
description: Detects Keylime registrar errors due to type mismatch in agent_id
logsource:
    product: keylime
    service: registrar
detection:
    selection:
        - "TypeError: agent_id must be str"
        - "ValueError: agent_id"
    condition: selection
falsepositives:
    - Legitimate code changes
level: medium

Suricata Rule

alert tcp any any -> any 8890 (msg:"CVE-2025-1057 Keylime Registrar Type Error"; content:"TypeError"; content:"agent_id"; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Downgrade Keylime to version 7.11.0 until a patch is released.
2. Short-term: Apply a manual patch to the registrar code to convert bytes to str on read.
3. Long-term: Monitor the Keylime repository for an official fix (expected to be in 7.12.1 or later).
4. Prevention: Implement database migration scripts to convert existing bytes entries to str before upgrading.

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