ownCloud Auth Bypass CVE-2023-49105 Used to Exfiltrate 372 MB of Philippine Nuclear Records

A Chinese-speaking operator used an ownCloud authentication bypass disclosed in November 2023 to download 176 files, roughly 372 MB, from a Philippine nuclear research body. The material was not incidental. It included nuclear-material account records, research reactor core component documentation, historical fuel inventories, draft strategic plans covering 2023 through 2028, presentation decks, employee personal information, and a credential store holding BitLocker recovery keys, a KeePass database, and AxCrypt-encrypted files. CISA added the flaw, CVE-2023-49105, to the Known Exploited Vulnerabilities catalog on Thursday and set a Federal Civilian Executive Branch remediation deadline of August 30, 2026.

The bug: signed WebDAV requests with an empty secret

CVE-2023-49105 carries a CVSS score of 9.8 and affects ownCloud core versions 10.6.0 through 10.13.0. It was fixed in 10.13.1. The defect is an authentication bypass in the WebDAV API: if an account has no signing key configured, which is the default state, an attacker who knows a valid username can construct a pre-signed WebDAV URL that the server accepts as an authenticated action by that user. No password, no token, no session. From there the attacker can read, modify, or delete any file that account can reach.

That default is what turns a theoretical signature check into a free pass. The signing secret is empty until an administrator sets one, so the server validates a signature computed over nothing and returns the file. Username enumeration on a self-hosted file server is rarely hard, and in this case the operator only needed four of them.

How the operation was found

Hunt.io identified an open directory on the host 31.58.209[.]241. The directory was not a test bed. It staged five custom Python scripts implementing the CVE-2023-49105 exploit, open-source offensive tooling including Sliver, Metasploit, and Mettle, and the stolen data itself sorted into five staging directories. Four of the Python scripts targeted a single ownCloud account each. The fifth enumerated the WebDAV directory tree and logged every download attempt, which is how the file and byte counts are known with precision rather than estimated.

The largest single item in the haul was a 192 MB SQL dump of a ZKTeco BioTime attendance and personnel database. That is more than half the total volume by size and is the kind of artifact that yields badge identifiers, shift patterns, and full employee rosters for a facility that handles nuclear material. Combined with the BitLocker keys and KeePass database, the operator walked away with both a personnel map and the means to open encrypted material collected later.

A second Philippine target

The same infrastructure held exfiltrated data from a marine engineering and shipbuilding company that services the Philippine Navy. That intrusion ran through the company's WordPress site rather than a file server. The operator exploited CVE-2024-28000, a critical privilege escalation in the LiteSpeed Cache plugin also rated CVSS 9.8, to obtain elevated access. A separate script in the open directory, brute_xmlrpc.py, ran an XML-RPC brute-force attack against the same site, giving the operator a credential-guessing path that did not depend on the plugin flaw at all. Two independent routes to the same target is a deliberate redundancy, not opportunism.

Analysis of the WordPress source also surfaced a second, likely unrelated compromise using EtherHiding: HTML content pulled from an Ethereum smart contract, rendering a Google verification page in the ClickFix pattern. The lure launches pcalua.exe to invoke mshta.exe and fetch a VBScript dropper. Two distinct actors on one small business web property is a reasonable expectation for any internet-facing WordPress install that has gone unpatched.

Attribution and intent

Attribution here rests on language artifacts, not infrastructure overlap or malware lineage. Simplified Chinese appears in source code comments, docstrings, log output, and the folder names used to sort stolen data. That supports a Chinese-speaking operator. It does not by itself establish state direction, and Hunt.io explicitly leaves open whether the operator is state-affiliated, contracted, or independent. Treat the targeting logic as the stronger signal: a nuclear research body and a Navy shipbuilding supplier, both Philippine, both consistent with collection priorities around South China Sea tensions.

Why a 2023 CVE still works in 2026

Self-hosted file sync platforms sit in a maintenance blind spot. They are often stood up by a research or engineering team rather than IT, they hold exactly the documents worth stealing, and they get patched on nobody's schedule. Nearly three years passed between the ownCloud advisory and this KEV listing. The exploit requires no dropper, no persistence, and no lateral movement to succeed. A handful of Python scripts against a WebDAV endpoint produced 372 MB of sensitive material.

What to do now

• Inventory every ownCloud instance, including shadow deployments on research and lab networks, and confirm the core version. Anything from 10.6.0 through 10.13.0 is exploitable.
• Upgrade to ownCloud core 10.13.1 or later. If an immediate upgrade is not possible, configure a signing key for every account and restrict WebDAV endpoint exposure to VPN or allowlisted ranges.
• Pull WebDAV access logs and look for unauthenticated GET activity, sequential directory enumeration, and bulk downloads. The fifth script logged every attempt, which means the corresponding server-side traffic is there to find.
• Search for the staging host 31.58.209[.]241 in firewall, proxy, and NetFlow records, and hunt for Sliver, Metasploit, and Mettle implant indicators on hosts adjacent to any exposed instance.
• Patch WordPress LiteSpeed Cache against CVE-2024-28000 and disable XML-RPC where it is not required. Both were used against the second victim.
• Rotate anything that was stored in the file share. BitLocker recovery keys, KeePass vaults, and encrypted archives in the haul must be treated as compromised, not merely exposed.

The practical takeaway is narrow and repeatable. Credential material stored inside a document repository inherits that repository's weakest authentication path. When the path is an unauthenticated WebDAV read, the KeePass database and the BitLocker keys leave with everything else, and the incident scope stops being one file server.