Microsoft Windows NT 4.0 Keystream credentials management

CVSS Meta Temp Score
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CTI Interest Score
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4.8$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Microsoft Windows NT 4.0. The affected element is an unknown function of the component Keystream Handler. The manipulation leads to credentials management. This vulnerability is referenced as CVE-1999-0994. Furthermore, an exploit is available. This vulnerability has a historic impact because of its background and how it was received. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Microsoft Windows NT 4.0 (Operating System). It has been rated as critical. This issue affects an unknown functionality of the component Keystream Handler. The manipulation with an unknown input leads to a credentials management vulnerability. Using CWE to declare the problem leads to CWE-255. Impacted is confidentiality. The summary by CVE is:

Windows NT with SYSKEY reuses the keystream that is used for encrypting SAM password hashes, allowing an attacker to crack passwords.

The weakness was published 12/16/1999 with BindView as MS99-056 as confirmed bulletin (Technet). The advisory is shared at microsoft.com. The identification of this vulnerability is CVE-1999-0994. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are unknown but a public exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/19/2026). MITRE ATT&CK project uses the attack technique T1552 for this issue. Due to its background and reception, this vulnerability has a historic impact.

It is declared as proof-of-concept. We expect the 0-day to have been worth approximately $25k-$100k.

Upgrading to version XP or 2000 eliminates this vulnerability. Applying the patch MS99-056 is able to eliminate this problem. The bugfix is ready for download at microsoft.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at X-Force (3950), SecurityFocus (BID 873†) and Vulnerability Center (SBV-3135†). Similar entry is available at VDB-15066. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 4.8

VulDB Base Score: 5.3
VulDB Temp Score: 4.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Credentials management
CWE: CWE-255
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Windows XP/2000
Patch: MS99-056

Timelineinfo

12/16/1999 🔍
12/16/1999 +0 days 🔍
12/16/1999 +0 days 🔍
12/16/1999 +0 days 🔍
12/10/2003 +1455 days 🔍
06/22/2014 +3847 days 🔍
04/19/2026 +4319 days 🔍

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: MS99-056
Organization: BindView
Status: Confirmed

CVE: CVE-1999-0994 (🔍)
GCVE (CVE): GCVE-0-1999-0994
GCVE (VulDB): GCVE-100-15065
X-Force: 3950
SecurityFocus: 873 - NT Syskey Reused Keystream Vulnerability
Vulnerability Center: 3135 - [MS99-056] Windows NT with SYSKEY Allows an Attacker to Crack Passwords, Low

scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 06/22/2014 16:01
Updated: 04/19/2026 23:25
Changes: 06/22/2014 16:01 (68), 04/19/2026 23:25 (16)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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