CVE-2024-49849 Overview
CVE-2024-49849 affects a broad set of Siemens engineering and runtime products, including SIMATIC STEP 7, SIMATIC WinCC, SIMATIC WinCC Unified, SIMATIC S7-PLCSIM, SIMOCODE ES, SIMOTION SCOUT TIA, SINAMICS Startdrive, SIRIUS ES, and TIA Portal Cloud. The vulnerability results from improper sanitization of user-controllable input during log file parsing. An attacker who convinces a local user to open a crafted log file can trigger a type confusion condition and execute arbitrary code inside the affected application. The issue is tracked under [CWE-502: Deserialization of Untrusted Data].
Critical Impact
Successful exploitation grants arbitrary code execution in the context of the engineering or HMI application, providing a pivot into operational technology (OT) environments.
Affected Products
- SIMATIC STEP 7 / STEP 7 Safety V16–V19 (fixed in V17 Update 9 and V19 Update 4)
- SIMATIC WinCC / WinCC Unified V16–V19 (fixed in V17 Update 9 and V19 Update 4)
- SIMATIC S7-PLCSIM V16/V17, SIMOCODE ES V16–V19, SIMOTION SCOUT TIA V5.4–V5.6 (fixed in V5.6 SP1 HF7), SINAMICS Startdrive V16–V19, SIRIUS Safety/Soft Starter ES V17–V19, and TIA Portal Cloud V16–V19 (fixed in V5.2.1.1)
Discovery Timeline
- 2024-12-10 - CVE-2024-49849 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-49849
Vulnerability Analysis
The vulnerability lives in the log file parsing logic shared across the affected Siemens engineering suites. When the application reads a log file, it fails to validate structural attributes of embedded objects before dispatching them to type-specific handlers. An attacker crafts a log file that declares one object type while supplying data compatible with another, causing the parser to interpret memory as the wrong type. This type confusion enables control over pointers and function dispatch, leading to arbitrary code execution within the process. Because these products run with engineering or operator privileges on OT workstations, a successful attack can alter PLC projects, HMI configurations, and safety logic.
Root Cause
The underlying weakness is [CWE-502: Deserialization of Untrusted Data]. The log parser deserializes attacker-controlled fields without enforcing type integrity, so mismatched objects are treated as trusted instances during runtime dispatch.
Attack Vector
Exploitation requires local access and user interaction. An attacker delivers a malicious log file via phishing, a shared engineering repository, a compromised project archive, or a removable device. When a user opens the file in an affected TIA Portal or WinCC component, the parser reaches the vulnerable code path and executes the embedded payload.
No verified public proof-of-concept code is available. Refer to the Siemens Security Advisory SSA-800126 for technical details.
Detection Methods for CVE-2024-49849
Indicators of Compromise
- Unexpected child processes (for example, cmd.exe, powershell.exe, or rundll32.exe) spawned by TIA Portal, WinCC, or related Siemens engineering executables
- Log files (.log, .dmp, project trace files) received from untrusted sources or found outside the standard TIA Portal project directories
- File writes or registry modifications occurring immediately after a Siemens engineering application opens a log file
Detection Strategies
- Hunt for anomalous process trees where SIMATIC or TIA Portal binaries launch scripting interpreters or network utilities
- Alert on unsigned or newly written DLLs loaded by Siemens engineering processes shortly after log file access
- Correlate endpoint telemetry with file-open events on .log-style artifacts arriving through email, USB, or shared drives
Monitoring Recommendations
- Baseline expected parent-child relationships for engineering workstations and flag deviations
- Forward engineering-workstation telemetry to a central data lake for cross-host correlation and retrospective hunting
- Monitor outbound connections from OT engineering hosts, which should be tightly scoped and rarely change
How to Mitigate CVE-2024-49849
Immediate Actions Required
- Update affected products to the fixed versions listed in Siemens Security Advisory SSA-800126, including STEP 7 / WinCC V17 Update 9, V19 Update 4, SIMOTION SCOUT TIA V5.6 SP1 HF7, and TIA Portal Cloud V5.2.1.1
- Restrict engineering workstations to authorized operators and enforce application allowlisting
- Treat log files, trace files, and project archives from external parties as untrusted until validated
Patch Information
Siemens has released fixed versions for a subset of affected products. STEP 7, STEP 7 Safety, WinCC, and WinCC Unified are fixed in V17 Update 9 and V19 Update 4. SIMOTION SCOUT TIA is fixed in V5.6 SP1 HF7 and TIA Portal Cloud in V5.2.1.1. For products where no fix is listed (V16, V18, SIMOCODE ES, SINAMICS Startdrive, SIRIUS ES, SIMATIC S7-PLCSIM V16/V17), apply the workarounds below and monitor the vendor advisory for updates.
Workarounds
- Only open log files, project archives, and diagnostic dumps from trusted, verified sources
- Segment OT engineering networks from IT and internet-facing systems following ISA/IEC 62443 guidance
- Apply the Siemens Operational Guidelines for Industrial Security to reduce exposure while patches are staged
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
