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Data Access ComponentsApplication · Microsoft

CVE-1999-1011

HIGH · 10.0 CVSS v2.0 Published 1999-07-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The Remote Data Service (RDS) DataFactory component of Microsoft Data Access Components (MDAC) in IIS 3.x and 4.x exposes unsafe methods, which allows remote attackers to execute arbitrary commands.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Remote Data Service (RDS) DataFactory component in Microsoft Data Access Components (MDAC) on IIS 3.x and 4.x exposes unsafe methods to remote attackers, allowing arbitrary command execution on the affected server.

MitigationDisable or remove the RDS DataFactory component and associated MDAC components from affected IIS installations, or upgrade to patched versions of MDAC and IIS.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Data Access ComponentsApplication
Affected:= 1.5= 2.0= 2.1
Index ServerApplication
Affected:= 2.0
Internet Information ServerApplication
Affected:= 3.0= 4.0
Site ServerApplication
Affected:= 3.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify IIS version
    Check the IIS version installed on the server. For IIS 3.0, check the registry key HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\MajorVersion or use the inetmgr snap-in. For IIS 4.0, check via the Microsoft Management Console or the About dialog in the IIS Manager.
    Affected if The installed IIS version is 3.0 or 4.0, matching the affected versions in the CVE.
  2. Identify installed MDAC version
    Check the MDAC version by querying the registry key HKLM\SOFTWARE\Microsoft\DataAccess\Version or by running the system information utility and looking for the Data Access Components version string.
    Affected if The installed MDAC version is 1.5, 2.0, or 2.1, which are the affected versions listed in this CVE.
  3. Confirm RDS DataFactory component presence
    Locate and inspect the msadcs.dll file in the /msadc/ directory or the Scripts virtual directory on the IIS server. Also check the registry key HKLM\SOFTWARE\Microsoft\DataAccess\DataFactory\Handler for registered handlers.
    Affected if The msadcs.dll file exists and is accessible on the IIS server, indicating the RDS DataFactory component is installed.
  4. Verify RDS functionality is enabled
    Attempt to access the RDS endpoint by requesting the URL pattern http://server/msadc/msadcs.dll or check the IIS metabase for enabled RDS or DataFactory application mappings under the RDS or MSADC virtual directories.
    Affected if The RDS DataFactory component is enabled and accessible, allowing remote data service requests to be processed.

The environment is affected if IIS 3.0 or 4.0 is running with MDAC 1.5, 2.0, or 2.1 installed and the RDS DataFactory component (msadcs.dll) is present and enabled, allowing remote attackers to execute arbitrary commands through exposed unsafe methods.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable or remove the RDS DataFactory component and associated MDAC components from affected IIS installations, or upgrade to patched versions of MDAC and IIS.

Recommended fix Moderate confidence

MDAC 2.5 SP2 or later; IIS 5.0 or later with current security updates

  1. Disable the RDS (Remote Data Service) DataFactory component by removing or restricting access to the msadc/msadcs.dll virtual directory
  2. If RDS is required, apply the Microsoft Security Bulletin MS99-025 patch which fixes this vulnerability
  3. Restrict permissions on the MSDAC components to prevent unauthorized access
  4. Consider upgrading to a patched version of MDAC (2.5 Service Pack 2 or later includes the fix)
  5. As a further mitigation, disable the RDS service in IIS if not needed
Caveat Disabling RDS may break applications that depend on Remote Data Service functionality

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Data Access Components Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-1999-1011 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data