A vulnerability has been identified in SIMATIC PCS 7 V8.0 and earlier (All versions), SIMATIC PCS 7 V8.1 (All versions < V8.1 with WinCC V7.3 Upd 19), SIMATIC PCS 7 V8.2 (All versions < V8.2 SP1 with WinCC V7.4 SP1 Upd 11), SIMATIC PCS 7 V9.0 (All versions < V9.0 SP2 with WinCC V7.4 SP1 Upd11), SIMATIC WinCC Professional (TIA Portal V13) (All versions), SIMATIC WinCC Professional (TIA Portal V14) (All versions < V14 SP1 Upd 9), SIMATIC WinCC Professional (TIA Portal V15) (All versions < V15.1 Upd 3), SIMATIC WinCC Runtime Professional V13 (All versions), SIMATIC WinCC Runtime Professional V14 (All versions < V14.1 Upd 8), SIMATIC WinCC Runtime Professional V15 (All versions < V15.1 Upd 3), SIMATIC WinCC V7.2 and earlier (All versions), SIMATIC WinCC V7.3 (All versions < V7.3 Upd 19), SIMATIC WinCC V7.4 (All versions < V7.4 SP1 Upd 11), SIMATIC WinCC V7.5 (All versions < V7.5 Upd 3). The SIMATIC WinCC DataMonitor web application of the affected products allows to upload arbitrary ASPX code. The security vulnerability could be exploited by an authenticated attacker with network access to the WinCC DataMonitor application. No user interaction is required to exploit this vulnerability. The vulnerability impacts confidentiality, integrity, and availability of the affected device. At the stage of publishing this security advisory no public exploitation is known.
Weakness
The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product’s environment.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Simatic_pcs_7 |
Siemens |
8.0 (including) |
8.0 (including) |
| Simatic_pcs_7 |
Siemens |
8.1 (including) |
8.1 (including) |
| Simatic_pcs_7 |
Siemens |
8.2 (including) |
8.2 (including) |
| Simatic_pcs_7 |
Siemens |
9.0 (including) |
9.0 (including) |
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- For example, limiting filenames to alphanumeric characters can help to restrict the introduction of unintended file extensions.
- Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
References