Full Report
SINEC OS before V4.0 contains multiple vulnerabilities. Siemens has released a new version for RUGGEDCOM RST2428P and recommends to update to the latest version.
Analysis Summary
This summary provides a technical overview of the security vulnerabilities identified in SINEC OS as documented in Siemens Security Advisory SSA-253495.
# Vulnerability: Multiple Vulnerabilities in SINEC OS
## CVE Details
The advisory covers several vulnerabilities. Key highlights include:
- **CVE-2026-35535 (Sudo):** CVSS 7.4 (High) | CWE-271: Privilege Dropping / Lowering Errors
- **CVE-2026-26157/CVE-2026-26158 (BusyBox):** CVSS 7.0 (High) | CWE-73: External Control of File Name or Path
- **CVE-2025-40214 (Linux Kernel):** CVSS 7.0 (High) | CWE (Logic error in AF_UNIX GC)
- **CVE-2026-41918 (Web UI):** CVSS 5.7 (Medium) | CWE-525: Use of Web Browser Cache
- **Linux Kernel (tcp_bpf):** CVSS 5.5 (Medium) | CWE-20: Improper Input Validation
## Affected Systems
- **Products:** RUGGEDCOM RST2428P (6GK6242-6PA00)
- **Versions:** All versions prior to SINEC OS V4.0
- **Configurations:** Systems utilizing BPF (Berkeley Packet Filter), AF_UNIX sockets, BusyBox extraction utilities, or the Sudo mailer functionality.
## Vulnerability Description
SINEC OS prior to V4.0 integrates several third-party components (Linux Kernel, BusyBox, Sudo) containing flaws:
1. **Linux Kernel (AF_UNIX):** A failure to initialize `scc_index` in the AF_UNIX garbage collector allows for a race condition where the kernel misidentifies alive sockets as dead, potentially leading to memory corruption or instability.
2. **Linux Kernel (tcp_bpf):** Improper handling of memory allocation failures during `sk_msg_cork_bytes` operations. If a fault occurs, the system fails to revert forwarded memory allocations.
3. **Sudo:** A flaw in the privilege drop mechanism when executing a mailer. If a `setuid` call fails, the process continues with elevated privileges.
4. **BusyBox:** Improper validation of hardlinks/symlinks in tar archives allows for arbitrary file overwrites outside the destination directory.
5. **Web UI:** Sensitive configuration data is stored in the browser cache, accessible to other users of the same workstation.
## Exploitation
- **Status:** PoC availability varies; syzbot reproducers exist for kernel flaws. No known exploitation in the wild for the SINEC OS implementation specifically.
- **Complexity:** Medium to High (Many require local access or specific race conditions).
- **Attack Vector:** Varies; primarily Local (Kernel/Sudo/BusyBox) and Network (Web UI).
## Impact
- **Confidentiality:** High (Access to sensitive configuration and system files).
- **Integrity:** High (Arbitrary file overwrite and privilege escalation).
- **Availability:** High (Kernel "splats" and potential system crashes).
## Remediation
### Patches
- **SINEC OS V4.0:** Siemens recommends updating the RUGGEDCOM RST2428P to this version or later to resolve these vulnerabilities.
### Workarounds
- Limit local shell access to trusted administrators only.
- Clear browser caches after modifying device configurations via the Web UI.
- Avoid extracting untrusted archives using integrated BusyBox tools until patched.
## Detection
- **Indicators of Compromise:** Unusual kernel "splat" warnings in system logs (specifically `inet_sock_destruct` or `unix_walk_scc`).
- **Detection Methods:** Monitor for unauthorized `setuid` failures in system logs and audit file system integrity for unexpected changes in sensitive directories.
## References
- Siemens ProductCERT: hxxps://www[.]siemens[.]com/cert/advisories
- Advisory Link: hxxps://cert-portal[.]siemens[.]com/productcert/html/ssa-253495[.]html