Title: NT Help File Buffer Overflow Vulnerability
Severity: MODERATE
Description:
Lax permission in the Windows NT help file folder and a buffer overflow in the Help utility may allow malicious users to gain Administrator privileges.
The Windows NT Help utility parses and displays help information for selected applications. The help files are stored in the %SystemRoot%\help directory. The default permissions in this directory allow any user to add new files.
A buffer overflow exists in the Help utility when it attempts to read a .cnt file with an overly long heading string. Content tab informaton files (".cnt") are generated when rich text format files (".rtf") are translated to help files (".hlp"). If the string is longer than 507 bytes winhlp32 truncates the entry and the buffer overflow does not occur.
A malicious user can create a custom .cnt help file with executable code in an entry string which when stored in the help directory and viewed by an unsuspecting user can grant them that users privileges.
The vulnerability is not limited by the permissions of the help file directory as the Help utility will search for a .cnt file first in its execution directory before looking in the help file directory.
Affected Products:
- Microsoft Windows NT 4.0
- Microsoft Windows NT 4.0 SP1
- Microsoft Windows NT 4.0 SP2
- Microsoft Windows NT 4.0 SP3
- Microsoft Windows NT 4.0 SP4
- Microsoft Windows NT 4.0 SP5
- Microsoft Windows NT Enterprise Server 4.0
- Microsoft Windows NT Enterprise Server 4.0 SP1
- Microsoft Windows NT Enterprise Server 4.0 SP2
- Microsoft Windows NT Enterprise Server 4.0 SP3
- Microsoft Windows NT Enterprise Server 4.0 SP4
- Microsoft Windows NT Enterprise Server 4.0 SP5
- Microsoft Windows NT Server 4.0
- Microsoft Windows NT Server 4.0 SP1
- Microsoft Windows NT Server 4.0 SP2
- Microsoft Windows NT Server 4.0 SP3
- Microsoft Windows NT Server 4.0 SP4
- Microsoft Windows NT Server 4.0 SP5
- Microsoft Windows NT Terminal Server 4.0
- Microsoft Windows NT Terminal Server 4.0 SP1
- Microsoft Windows NT Terminal Server 4.0 SP2
- Microsoft Windows NT Terminal Server 4.0 SP3
- Microsoft Windows NT Terminal Server 4.0 SP4
- Microsoft Windows NT Terminal Server 4.0 SP5
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Workstation 4.0 SP1
- Microsoft Windows NT Workstation 4.0 SP2
- Microsoft Windows NT Workstation 4.0 SP3
- Microsoft Windows NT Workstation 4.0 SP4
- Microsoft Windows NT Workstation 4.0 SP5
References:
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