IBM Db2 is a widely used database product in enterprise environments. In March 2023, a serious privilege escalation vulnerability was uncovered: CVE-2023-27558 (IBM Security Bulletin), affecting Db2 versions 10.5, 11.1, and 11.5 on Windows. This vulnerability is tracked by IBM X-Force ID: 249194.

The root cause? At least one Db2 Windows service is installed with an unquoted service path. This oversight allows a local attacker to gain higher privileges—up to SYSTEM—by placing a malicious executable along the service path.

This post gives you a clear, step-by-step breakdown of the vulnerability, including code snippets, practical exploitation, and mitigation tips.

What is an Unquoted Service Path?

When Windows launches a service, it uses the full path to the service's executable. If this path contains spaces and is not surrounded by quotes, Windows may misinterpret where the executable is, especially if an attacker is able to plant an executable earlier in the path.

Example

C:\Program Files\IBM\DB2\BIN\DB2SVC.EXE

...and so on

If an attacker drops a Program.exe in C:\, Windows might run that file as SYSTEM.

Db2 11.5

Check IBM's official security advisory for more info.

Db2 service is installed without quotes in the service path.

- The directories in the path have write permissions for non-admin users (often true in poorly configured environments).

Find Unquoted Service Paths

First, enumerate all services and look for unquoted paths with spaces.

Get-WmiObject win32_service | 
    where { $_.PathName -notlike '"*"' -and $_.PathName -like "* *" } |
    Select-Object Name, PathName

Look for Db2 services with paths like

C:\Program Files\IBM\DB2\BIN\Db2Service.exe

Check Permissions

If possible, check if you can write to any segment of the path, e.g. C:\Program Files\.

> Keep in mind: Most Windows installations protect C:\Program Files\—so real attacks often rely on misconfigurations or other writable locations.

Imagine the path is exactly

C:\Program Files\IBM\DB2\BIN\Db2Service.exe

C:\Program Files\IBM\DB2\BIN\Db2Service.exe

If you can drop Program.exe in C:\, that will get executed as SYSTEM when the service starts.

> Example exploit code: (Dropper, not payload)
>
>

> # Place a binary as "C:\\Program.exe"
> with open("C:\\Program.exe", "wb") as f:
>     f.write(b"MZ...")  # Your malicious binary
>

PoC: Minimal Demonstration

Since most users cannot write to C:\, here’s how you might simulate this in a VM.

REM Compile hello.c to hello.exe (simple reverse shell or calc launcher)
REM Place it as "C:\Program.exe"
REM Restart the vulnerable Db2 service via "services.msc" or:
net stop DB2
net start DB2

IMPORTANT: This is for educational purposes on test systems only.

List all unquoted service paths

Get-WmiObject win32_service | 
    where { $_.PathName -notlike '"*"' -and $_.PathName -like "* *" } |
    Select-Object Name, PathName

Quote all service paths in their registry entries under

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\<ServiceName>\ImagePath

Change

C:\Program Files\IBM\DB2\BIN\Db2Service.exe

TO

"C:\Program Files\IBM\DB2\BIN\Db2Service.exe"

2. Restrict folder permissions so unprivileged users cannot write to any folder on the execution path.

References

- IBM Security Bulletin: CVE-2023-27558
- MITRE CVE-2023-27558
- Microsoft: Unquoted Service Path vulnerability
- OWASP: Unquoted Service Paths

Conclusion

CVE-2023-27558 is a classic example of how a simple Windows misconfiguration can lead to full system compromise. All Db2 administrators should audit their services ASAP and apply needed fixes. Patch management, strong folder permissions, and a careful eye on service configuration will keep your systems safe.

Timeline

Published on: 07/10/2023 16:15:00 UTC
Last modified on: 08/18/2023 14:15:00 UTC