CVE-2025-7976 Overview
CVE-2025-7976 is a deserialization of untrusted data vulnerability in Anritsu ShockLine. The flaw resides in the parsing logic for .chx files, where user-supplied data is deserialized without proper validation. Attackers can leverage this weakness to execute arbitrary code in the context of the current process. Exploitation requires user interaction: the target must open a malicious CHX file or visit a malicious page that delivers one. The Zero Day Initiative tracked this issue as ZDI-CAN-26882 and published advisory ZDI-25-648. The vulnerability is classified under [CWE-502] Deserialization of Untrusted Data.
Critical Impact
Successful exploitation grants arbitrary code execution on workstations running Anritsu ShockLine, enabling attackers to compromise engineering and measurement systems through a single malicious file.
Affected Products
- Anritsu ShockLine (all versions per the ZDI advisory)
- Systems processing .chx measurement data files
- Engineering workstations running vector network analyzer software
Discovery Timeline
- 2025-09-02 - CVE-2025-7976 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-7976
Vulnerability Analysis
The vulnerability stems from how Anritsu ShockLine processes CHX files. CHX files store calibration and measurement data for vector network analyzer workflows. ShockLine reconstructs in-memory objects from these files during loading.
The parser deserializes attacker-controlled content without validating type information or object graphs. This allows a crafted CHX file to inject gadget chains that execute when the runtime reconstructs the object. Code execution occurs in the security context of the user running ShockLine, which on most lab and engineering systems carries broad local privileges.
The attack requires local access in the sense that the file must be opened on the target machine, but delivery via email, removable media, or a download link is straightforward. This pattern aligns with [CWE-502] and follows a long history of unsafe deserialization in file-based application formats.
Root Cause
The parsing routine for CHX files invokes a deserialization API on attacker-supplied bytes without restricting the set of permissible types. Without an allowlist or signature verification, the runtime instantiates arbitrary classes referenced inside the serialized stream. Constructor and setter side effects in those classes provide the path to arbitrary code execution.
Attack Vector
An attacker crafts a malicious .chx file containing a serialized payload referencing gadget classes available within the ShockLine process. The attacker distributes the file through phishing, a compromised website, shared lab storage, or USB media. When an engineer opens the file in ShockLine, the deserializer triggers the embedded chain and executes the attacker's code. Refer to the Zero Day Initiative Advisory ZDI-25-648 for additional technical context.
// No verified public proof-of-concept is available.
// The vulnerability is triggered by opening a crafted CHX file
// whose serialized object graph references attacker-chosen types.
Detection Methods for CVE-2025-7976
Indicators of Compromise
- Unexpected child processes spawned by the ShockLine application (for example, cmd.exe, powershell.exe, or rundll32.exe).
- CHX files arriving from external email, web downloads, or removable media outside of normal calibration workflows.
- Outbound network connections initiated by the ShockLine process to non-Anritsu infrastructure.
- New persistence artifacts (scheduled tasks, Run keys, services) created shortly after a CHX file is opened.
Detection Strategies
- Monitor process lineage where ShockLine is the parent and a shell, scripting host, or LOLBin is the child.
- Alert on file writes to startup, Run key, or scheduled task locations performed by the ShockLine process.
- Hunt for CHX files outside expected directories and correlate with user file-open events.
- Inspect serialized streams in CHX files for unexpected type references when sandbox detonation is possible.
Monitoring Recommendations
- Forward endpoint process, file, and network telemetry to a centralized data lake for correlation across engineering workstations.
- Apply behavioral analytics that flag deserialization-triggered code execution patterns regardless of file extension.
- Track inbound CHX file delivery via mail gateways, proxy logs, and removable media auditing.
How to Mitigate CVE-2025-7976
Immediate Actions Required
- Restrict CHX file handling to trusted internal sources and block CHX attachments at the mail gateway.
- Run ShockLine under a standard user account rather than a local administrator to limit blast radius.
- Apply application allowlisting to prevent ShockLine from launching scripting hosts or shells.
- Educate engineering staff on the risk of opening CHX files received from untrusted sources.
Patch Information
No vendor patch URL is listed in the available CVE data. Consult Anritsu directly and the Zero Day Initiative Advisory ZDI-25-648 for the latest remediation status, and apply vendor updates as soon as they become available.
Workarounds
- Open CHX files only from verified, internal calibration sources and reject files from external parties.
- Isolate ShockLine workstations on a segmented network with restricted outbound connectivity.
- Disable file association auto-open behavior for .chx and require manual import inside the application.
- Maintain endpoint protection with behavioral identification of post-exploitation activity originating from measurement software.
# Example: block CHX attachments at a Postfix mail gateway
# /etc/postfix/mime_header_checks
/name=[^>]*\.chx/ REJECT CHX attachments are not permitted by policy
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
