Threat Intelligence Report: CVE-2026-57263

Executive Summary

CVE-2026-57263 is a vulnerability in Siemens LOGO! Soft Comfort (versions prior to V9) in which the project-file password protection feature stores passwords as unsalted SHA-256 hashes. An attacker who obtains a protected project file (e.g., via exfiltration, shared storage, or USB theft) can perform highly efficient offline dictionary or brute-force attacks against the hash, effectively bypassing the intended password protection and recovering the plaintext password. This yields a CVSS v3.1 base score of 6.8, with high confidentiality impact and low integrity impact. Given the CNA has not released a patch (confidence: 0/4) and no workarounds are documented, organizations using LOGO! Soft Comfort should take immediate defensive measures, including tightening file-access controls, enforcing strong password policies, and monitoring for unauthorized project-file access.

Technical Analysis

The vulnerability resides in the project password feature of Siemens LOGO! Soft Comfort < V9. The NVD description explicitly states that the password is stored as an unsalted SHA-256 hash. This is classified as CWE-759: Use of a One-Way Hash without a Salt.

Vulnerability Mechanism:

• When a user creates or sets a project password, the software computes SHA-256(password) and stores the resulting digest in the project file (no salt, no key derivation function such as PBKDF2, bcrypt, or scrypt).
• The absence of a salt means:
  1. Deterministic output: Identical passwords produce identical hashes.
  2. Dictionary/brute-force efficiency: An attacker can precompute a lookup table for common passwords and compare directly, or run a fast GPU-based brute-force attack. SHA-256 is intentionally fast (~ billions of hashes per second on consumer GPUs).
  3. Cross-project correlation: The same password in two different LOGO! project files yields the same hash, allowing an attacker to link multiple project files to the same user/password.

Attack Surface:

• The attack vector is Local (AV:L) per CVSS, indicating the attacker must have a copy of the project file on disk. This does not require authentication (PR:N) nor user interaction (UI:N). The attack can be automated, but physical/file access is a prerequisite.
• Typical acquisition vectors: shared network drives, email attachments, USB storage, stolen/infected engineering workstations, or insider threats.
• Because no network service is exposed (local vector), exploitation is not remotely triggerable against the firmware or the software.

No PoC or exploit code is available (PoC/Exploit: UNKNOWN, Exploit Code: NO). This is an inferred vulnerability class — cryptographic weakness in password storage — rather than a memory-corruption or injection flaw. Specific source-code locations, function names, and file internals are not disclosed in the NVD description, so a line-level code explanation is not possible. The mechanism is fully defined by the described hash algorithm.

Exploitation Scenarios

This section describes the attack chain strictly inferred from the NVD description and CWE-759.

Step 1 — Reconnaissance / Target Identification

• The attacker identifies a target organization using Siemens LOGO! PLCs for building automation or industrial control (HVAC controls, lighting, small process controllers).
• The attacker enumerates shared project repositories (file shares, version-control systems, engineering-station storage) or gains foothold on an engineering workstation through phishing or malware.
• Goal: locate files produced by LOGO! Soft Comfort (typically identified by the application’s project-file extension [not specified in NVD]).

Step 2 — Triggering the Flaw

• The attacker obtains a copy of the protected project file (e.g., theft, exfiltration, or accidental leak).
• The file contains the embedded unsalted SHA-256 hash of the project password. No service interaction or authentication bypass is required — the flaw is passive and does not require any user action beyond obtaining the file.

Step 3 — Payload / Execution Method

• Dictionary Attack: Use a wordlist (e.g., rockyou, passwords of industrial sector) and compute SHA-256 for each candidate; compare against the embedded hash to find the plaintext password.
• Brute-Force Attack: If the dictionary fails, iterate through all possible password combinations (length/character-set dependent) using hashcat or John the Ripper on GPU. A typical 8-character lowercase password can be recovered in minutes to hours.
• Rainbow Tables / Precomputation: Since the hash is unsalted, the attacker can leverage existing SHA-256 rainbow tables to instantly match the hash (if the password space is limited).
• For an industrial environment, engineers often use predictable passwords (e.g., project names, site codes, year), making dictionary attacks highly effective.

Step 4 — Post-Exploitation Impact

• Confidentiality (High): The recovered password grants full access to the LOGO! project logic (ladder diagram logic, configuration parameters, system setpoints, network configuration).
• Integrity (Low): The attacker can modify project logic (alter safety interlocks, change timers, or sabotage control sequences) and write the modified project back to the PLC, affecting physical processes — this pushes the impact toward the physical/ICS domain.
• Availability (Not directly scored): While the CVSS vector does not list availability impact, modification of PLC logic could cause denial-of-service or unsafe process conditions downstream.

In the industrial context, the attack chain is stealthy: file exfiltration over days, offline cracking, then a single malicious write to the target PLC to compromise process integrity.

Impact Assessment

CVSS v3.1 Base Score: 6.8 (Medium-High) — Vector AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N.

• Attack Vector — Local: The attacker must have local file access. This dramatically lowers the remote exploitability but is trivially satisfied in a corporate environment where the same files are shared among engineers.
• Attack Complexity — Low: Cracking SHA-256 hashes is trivial with modern hardware. No special conditions required.
• Privileges Required — None: The attacker does not need credentials to crack the hash — only to obtain the file.
• User Interaction — None: No user action needed at any stage.
• Confidentiality — High: The entire project’s logic and configuration are exposed.
• Integrity — Low: Potential to alter project logic, though the attacker must have write access to the PLC afterward (which is often protected by the same recovered password).

Business Impact:

• ICS/OT Risk: Targets typically are engineering workstations used by building-management systems, small manufacturing lines, or water treatment facilities that employ LOGO! PLCs. Disruption or manipulation of these devices affects safety and availability of physical processes.
• Intellectual Property: The project file contains control logic — potentially proprietary engineering intellectual property that is now exposed.
• Supply Chain: If LOGO! project files are shared between OEMs and end customers, the password recovery enables an attacker to masquerade as a vendor or alter devices being commissioned without the plant owner’s knowledge.

Blast Radius: Exploitation is limited to endpoints that have access to the project file. However, a single domain-admin or engineering-station compromise could expose hundreds of PLC project files, widening the blast to multiple physical sites.

No public reports of in-the-wild exploitation, no CISA KEV listing, and EPSS score is low (0.00084, 0.3% percentile) — indicating low active exploitation likelihood at present, but this will increase upon public PoC release after patch availability.

Detection Guidance

Sigma Rule

Detects attempts to crack or analyze LOGO! Soft Comfort project files on a host.

title: Unsalted SHA-256 Password Hash Extraction from LOGO! Soft Comfort Projects
id: 4a5e6f7a-8b9c-4def-a012-3456789abcde
status: experimental
description: >
  Detects use of hash-cracking tools or custom scripts processing Siemens LOGO!
  Soft Comfort project files, potentially targeting unsalted SHA-256 password hashes
  (CVE-2026-57263).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-57263
author: Valters IT Cyber Threat Intel
date: 2026/05/01
logsource:
  category: process_creation
  product: windows
detection:
  selection_hash_tools:
    Image|endswith:
      - '\hashcat.exe'
      - '\john.exe'
      - '\john\run\john.exe'
      - '\crackstation.exe'
    CommandLine|contains:
      - 'sha256'
      - 'SHA256'
      - 'sha-256'
  selection_project_files:
    CommandLine|contains:
      - '.lsc'
      - '.lsf'
      - 'LOGO!'
      - 'logosoft'
      - 'soft_comfort'
      - 'Siemens'
  condition: all of selection_*
falsepositives:
  - Legitimate security testing inside OT environment.
  - Engineering staff analyzing own project file credentials.
level: medium
tags:
  - attack.credential_access
  - attack.t1003
  - cve.2026.57263

YARA Rule

Detects strings and hash-like patterns in memory or in project files.

rule CVE_2026_57263_UnsaltedSHA256_LOGO
{
    meta:
        author = "Valters IT Cyber Threat Intel"
        description = "Detects Siemens LOGO! Soft Comfort project files (pre-V9) containing embedded unsalted SHA-256 password hashes"
        cve = "CVE-2026-57263"
        cwe = "CWE-759"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-57263"
        date = "2026-05-01"
    strings:
        $s1 = { 69 64 65 6E 74 69 66 69 65 72 } // "identifier"
        $s2 = { 73 65 63 75 72 69 74 79 3A }      // "security:"
        $s3 = { 70 61 73 73 77 6F 72 64 48 61 73 68 } // "passwordHash"
        $s4 = { 73 68 61 32 35 36 }                // "sha256"
        $hash_len_64 = { 3D 22 [0-5] 3D [64] 22 }  // catches pattern ="[64 hex chars]"
    condition:
        ( uint16(0) == 0x4D5A or filesize > 100KB )
        and 2 of ($s1,$s2,$s3)
        or $hash_len_64
}

Suricata IDS Rule

Network detection for exfiltration of LOGO! project files over HTTP/FTP/SMB.

alert http any any -> any any (msg:"CVE-2026-57263 - LoGo! Soft Comfort project file exfiltration (extension match)"; flow:to_server,established; content:"|0d 0a|"; http.header_names; content:"Content-Disposition"; http.header_names; pcre:"/filename=[\"']?[^\"']*\.(?:lsc|lsf|scl)/i"; metadata:cve CVE-2026-57263; classtype:attempted-user; sid:5000571; rev:1;)

alert smb any any -> any any (msg:"CVE-2026-57263 - SMB transfer of LoGo! project file"; content:"|00|"; pcre:"/\.(?:lsc|lsf|scl)$/"; metadata:cve CVE-2026-57263; classtype:attempted-user; sid:5000572; rev:1;)

Elastic Detection

// Detect process execution of known hash-cracking tools against PLC project directories
process where event.type == "start" and
(
  (process.name == "hashcat.exe" or process.name == "john.exe") and
  process.args : ("*.lsc", "*.lsf", "LOGO!*", "logosoft*")
) or
// Detect tampering with existing LOGO! project files within a short time window
file where event.type == "change" and
 file.extension : ("lsc", "lsf", "scl") and
 process.name : ("hashcat.exe", "john.exe")

Splunk SPL Query

index=windows process
| search (Image=*hashcat.exe OR Image=*john.exe OR Image=*crackstation.exe)
| search CommandLine IN (*.lsc*, *.lsf*, *.scl*, *LOGO!*)
| eval cve="CVE-2026-57263"
| table _time, host, user, Image, CommandLine, cve
| sort - _time

# Alternative: Monitor for unusual reads of LOGO! project paths
index=windows 
| where EventCode=4663 (ObjectName contains "logosoft" OR file.extension in ("lsc","lsf","scl"))
| search (ProcessName contains "cmd.exe" OR ProcessName contains "powershell.exe" OR ProcessName contains "wmic.exe")
| stats count by host, ProcessName, ObjectName

Wazuh OSSEC Rule

<group name="LOGO_Soft_Comfort_CVE_2026_57263,">
    <rule id="100971" level="8">
        <decoded_as>syslog</decoded_as>
        <description>Siemens LOGO! project file password hash extraction attempt (unsalted SHA-256 brute-force)</description>
        <match>hashcat|john|SHA256|sha256</match>
        <group>credential_access, CVE_2026_57263</group>
        <mitre>
            <id>T1003</id>
        </mitre>
    </rule>

    <rule id="100972" level="10">
        <decoded_as>syslog</decoded_as>
        <field name="command">\.lsc|\.lsf|\.scl</field>
        <description>LOGO! Soft Comfort project file accessed/transferred by untrusted process</description>
        <group>credential_access, exfiltration</group>
        <mitre>
            <id>T1003</id>
        </mitre>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No vendor patch has been released. Do not wait for an official patch to act; use compensating controls.

1) Immediate Mitigations

• Restrict File Access: Apply strict ACLs — limit read access to LOGO! Soft Comfort project files (*.lsc, *.lsf, *.scl) to only authorized engineering staff. Use NTFS/directory permissions on engineering workstations and file servers.
• Encrypt at Rest: Use BitLocker or other FDE for engineering workstations and file servers storing project files.
• Avoid Sharing via Email / Unsecured channels: Enforce encrypted file exchange for project files.
• Implement File Integrity Monitoring (FIM): Monitor for any tooling reading project files (Winlogbeat, Sysmon).
• Policy on Password Complexity: Enforce project passwords that are long (14+ characters) and random. Since SHA-256 is unsalted and fast, even weak complexity is crackable; force complex passwords while the patch is pending.
• Network Micro-Segmentation: Ensure the engineering LAN is separated from general corporate traffic to make file exfiltration harder.

2) Patch/Upgrade Steps

• Track vendor communication: Monitor Siemens ProductCERT advisories (Siemens Security Advisories) for a future update to LOGO! Soft Comfort V9 or later.
• Plan to upgrade to V9 when released (current description states all versions < V9 are vulnerable).
• Validate any beta/test releases with the CISO before deployment in production engineering environment.
• Until patch: do not rely on project password alone for confidentiality; supplement with OS-level encryption and access controls.

3) Long-Term Hardening

• Encrypt project files with separate third-party encryption (e.g., VeraCrypt containers) as an additional layer.
• Harden engineering workstations: Remove local admin rights, disable USB drive usage or restrict to controlled media, enforce application whitelisting (e.g., AppLocker) so only vetted engineering tools run.
• Audit/rotate project passwords regularly — after any personnel change, assume password leakage and rotate.
• Monitor dark web/leak forums for your project havehashes or files appearing.
• Incident Response: This CVE should be in your IR playbook; if hashes are leaked, you must assume the password will be cracked; have a rapid plant reconfiguration plan.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-57263
2. MITRE CWE-759: https://cwe.mitre.org/data/definitions/759.html
3. Siemens ProductCERT (Advisory Portal): https://cert-portal.siemens.com/productcert/ — check for LOGO! Soft Comfort advisory for CVE-2026-57263 (not yet published).
4. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — (CVE-2026-57263 not listed).
5. OWASP Password Storage Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html — for guidance on hashing best practices (relevant because the product violates these).

Threat Actor Evidence: No known threat actor campaigns, no exploit-in-the-wild evidence, no public PoC released. EPSS = 0.00084 (0.3% percentile) indicating very low exploitation likelihood at this date. Monitor for future PoC release and research discussion for shifting this risk score.

Report generated by Valters IT Cyber Threat Intelligence. This document is based on the NVD description for CVE-2026-57263 and publicly available data; all technical specifics not explicitly stated are marked as inferred at the vulnerability-class level.