CVE-2017-8923 Siemens CVE debrief

Who should care

Organizations operating Siemens RUGGEDCOM APE1808 devices in industrial control system environments should prioritize assessment and remediation. Security teams responsible for OT/ICS infrastructure, network administrators managing ruggedized networking equipment, and compliance officers tracking CVE coverage for critical infrastructure assets should review this advisory. Additionally, organizations using embedded PHP components in industrial products should evaluate their exposure to this class of memory safety vulnerability.

Technical summary

The vulnerability exists in PHP's zend_string_extend function located in Zend/zend_string.h. When processing string concatenation operations using the .= operator with long strings, the function fails to prevent length calculations that result in negative values. This integer handling defect can lead to memory corruption conditions that manifest as application crashes (denial of service) or potentially allow for more severe impacts depending on how the corrupted memory is subsequently accessed. The vulnerability is remotely exploitable without authentication, making it particularly dangerous for exposed applications. In the context of Siemens RUGGEDCOM APE1808, this vulnerability affects the embedded PHP components used by the device, potentially exposing industrial network infrastructure to compromise.

Defensive priority

critical

Recommended defensive actions

• Review Siemens security advisory SSA-455250 for detailed product-specific guidance on affected RUGGEDCOM APE1808 configurations
• Apply vendor-provided patches or updates for Palo Alto Networks Virtual NGFW V11.1.2-h3 or later as indicated in the remediation guidance
• Conduct inventory assessment to identify all RUGGEDCOM APE1808 deployments that may incorporate vulnerable PHP components
• Implement network segmentation to limit exposure of affected industrial control systems to untrusted networks
• Monitor for anomalous PHP script execution or unexpected application crashes that may indicate exploitation attempts
• Establish patch management procedures to address upstream PHP vulnerabilities in embedded industrial products
• Contact Siemens customer support to obtain specific patch and update information for affected deployments

Evidence notes

The vulnerability description is sourced from CISA CSAF advisory ICSA-24-102-04, which references Siemens security advisory SSA-455250. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C indicates network accessibility, low attack complexity, no required privileges or user interaction, and high impact across all three security dimensions. The advisory revision history shows this CVE was added in version 1.1 on May 14, 2024, as part of a batch of newly published upstream vulnerabilities affecting the product.

Official resources