Query: write Sigma for Detects creation of an ad-hoc Cloudflare Quick Tunnel, which can be used to tunnel local services such as HTTP, RDP, SSH
Matching passage: Sigma rule: Detects creation of an ad-hoc Cloudflare Quick Tunnel, which can be used to tunnel local services such as HTTP, RDP, SSH. Logsource: windows / process_creation. Rule: title: Cloudflared Quick Tunnel Execution id: 222129f7-f4dc-4568-b0d2-22440a9639ba related: - id: 7050bba1-1aed-454e-8f73-3f46f09ce56a type: similar - id: 9a019ffc-3580-4c9d-8d87-079f7e8d3fd4 type: similar status: test description: 'Detects creation of an ad-hoc Cloudflare Quick Tunnel, which can be used to tunnel local services such as HTTP, RDP, SSH and SMB. The free TryCloudflare Quick Tunnel will generate a random subdomain on trycloudflare[.]com, following a call to api[.]trycloudflare[.]com. The tool has been observed in use by threat groups including Akira ransomware. ' references: - https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/do-more-with-tunnels/trycloudflare/ - https://github.com/cloudflare/cloudflared - https://www.intrinsec.com/akira_ransomware/ - https://www.guidepointsecurity.com/blog/tunnel-vision-cloudflared-abused-in-the-wild/ author: Sajid Nawaz Khan tags: - attack.command-and-control - attack.t1090.001 date: 2023-12-20 logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: - \cloudflared.exe - \cloudflared-windows-386.exe - \cloudflared-windows-amd64.exe - Hashes|contains: - SHA256=2fb6c04c4f95fb8d158af94c137f90ac820716deaf88d8ebec956254e046cb29 - SHA256=b3d21940a10fdef5e415ad70331ce257c24fe3bcf7722262302e0421791f87e8 - SHA256=1fbd8362b2d2d2e6a5750ae3db69cd1815e6c1d31da48a98b796450971a8e039 - SHA256=0409c9b12f9d0eda86e461ed9bdabeefb00172b26322079681a0bdf48e68dc28 - SHA256=7cfb411d04bac42ef93d1f0c93c0a481e38c6f4612b97ae89d4702595988edc7 - SHA256=5b3c2d846ab162dc6bc595cce3a49de5731afde5d6060be7066d21b013a28373 - SHA256=ce95df7f69664c3df19b76028e115931919a71517b776da7b42d353e2ff4a670 - SHA256=1293525a19cfe3bc8296b62fbfe19f083632ed644a1c18c10b045a1d3030d81a - SHA256=af2b9161cfcb654b16408cd6b098afe9d1fb61a037d18d7090a119d4c0c8e0f0 - SHA256=39ddceb56a15798826a5fc4892fa2b474c444bb4d7a8bf2fa95e41cab10fa7a1 - SHA256=ccd11f2328023a0e7929e845d5b6e7bc783fb4650d65faef3ae090239d4bbce2 - SHA256=b6e5c5d2567ae8c69cc012ebcae30e6c9b5359d64a58d17ba75ec89f8bce71ac - SHA256=f813484ea441404f18caad96f28138e8aaf0cb256163c09c2ab8a3acab87f69f - SHA256=fc4a0802ab9c7409b892ca00636bec61e2acfc911bccfdeb9978b8ab5a2f828d - SHA256=083150724b49604c8765c1ba19541fa260b133be0acb0647fcd936d81f054499 - SHA256=44303d6572956f28a0f2e4b188934fb9874f2584f5c81fa431a463cfbf28083b - SHA256=5d38c46032a58e28ae5f7d174d8761ec3d64d186677f3ec53af5f51afb9bfd2f - SHA256=e1e70fa42059911bc6685fafef957f9a73fc66f214d070
Near-miss passage: Sigma rule: Detects the use of the `syslog` syscall with action code 5 (SYSLOG_ACTION_CLEAR), (4 is SYSLOG_ACTION_READ_CLEAR and 6 i. Logsource: linux / auditd. Rule: title: Clear or Disable Kernel Ring Buffer Logs via Syslog Syscall id: eca5e022-d368-4043-98e5-9736fb01f72f status: experimental description: 'Detects the use of the `syslog` syscall with action code 5 (SYSLOG_ACTION_CLEAR), (4 is SYSLOG_ACTION_READ_CLEAR and 6 is SYSLOG_ACTION_CONSOLE_OFF) which clears the kernel ring buffer (dmesg logs). This can be used by attackers to hide traces after exploitation or privilege escalation. A common technique is running `dmesg -c`, which triggers this syscall internally. ' references: - https://man7.org/linux/man-pages/man2/syslog.2.html - https://man7.org/linux/man-pages/man1/dmesg.1.html author: Milad Cheraghi date: 2025-05-27 modified: 2025-12-05 tags: - attack.defense-impairment - attack.t1685.006 logsource: product: linux service: auditd definition: 'Required auditd configuration: -a always,exit -F arch=b64 -S syslog -F a0=4 -k clear_dmesg_logs -a always,exit -F arch=b64 -S syslog -F a0=5 -k clear_dmesg_logs -a always,exit -F arch=b64 -S syslog -F a0=6 -k disable_dmesg_logs -a always,exit -F arch=b32 -S syslog -F a0=4 -k clear_dmesg_logs -a always,exit -F arch=b32 -S syslog -F a0=5 -k clear_dmesg_logs -a always,exit -F arch=b32 -S syslog -F a0=6 -k disable_dmesg_logs ' detection: selection: type: SYSCALL SYSCALL: syslog a0: - 4 - 5 - 6 condition: selection falsepositives: - System administrators or scripts that intentionally clear logs - Debugging scripts level: medium