CVE-1999-1277 in Backweb
Summary
by MITRE
BackWeb client stores the username and password in cleartext for proxy authentication in the Communication registry key, which could allow other local users to gain privileges by reading the password.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-1277 represents a critical security flaw in the BackWeb client software that persisted in the Windows registry system. This issue stems from improper credential storage practices where authentication credentials are saved in an unencrypted format within the Windows Communication registry key. The vulnerability specifically affects systems running the BackWeb client software, which was commonly used for web browsing and proxy connectivity in the late 1990s and early 2000s. The registry key structure used by BackWeb stored proxy authentication credentials in cleartext format, making them easily accessible to any local user with appropriate registry access permissions. This design flaw directly violates fundamental security principles regarding credential storage and access control, as it creates an unnecessary attack surface that exposes sensitive authentication information to unauthorized local users.
The technical implementation of this vulnerability involves the Windows registry's storage mechanism where BackWeb client applications write proxy authentication credentials to a specific registry key path without any encryption or access control measures. When a user configures proxy settings with authentication credentials, the software persists these details in the registry using standard Windows registry APIs without implementing any cryptographic protection. The cleartext storage approach means that any local user, including potentially malicious actors or compromised accounts, can access these registry entries through standard registry editing tools or programmatic access. This vulnerability specifically aligns with CWE-312, which addresses the exposure of sensitive information through cleartext storage, and represents a classic example of poor credential management practices that were common in legacy software implementations of that era.
The operational impact of this vulnerability extends beyond simple credential theft to encompass potential privilege escalation and unauthorized network access. Local users who gain access to the registry entries can immediately exploit the stored credentials to authenticate to proxy servers, potentially gaining access to restricted network resources, internal systems, or sensitive data that the original authenticated user was authorized to access. This vulnerability creates a significant risk for multi-user systems where different users share the same machine or where system administrators have multiple accounts with varying privilege levels. The attack vector requires only local system access, making it particularly dangerous as it can be exploited by any user with basic local privileges, including potentially compromised user accounts or malicious insider threats. This vulnerability essentially transforms local access into potential network-level privileges, creating a substantial security risk for organizations that rely on proxy authentication for network access control.
Mitigation strategies for CVE-1999-1277 should focus on immediate remediation through software updates and registry cleanup procedures. The primary solution involves updating to patched versions of the BackWeb client software that implement proper credential encryption and access controls. Organizations should immediately remove the vulnerable registry entries and ensure that no cleartext credentials remain accessible through standard system interfaces. System administrators should implement registry access controls using Windows permission settings to restrict access to sensitive registry keys, although this approach provides only partial protection given the vulnerability's nature. The recommended approach includes establishing regular security audits of registry entries, implementing proper credential management practices, and ensuring that legacy software components are either updated or removed from production environments. This vulnerability highlights the importance of following security best practices such as those outlined in the OWASP Top Ten and NIST guidelines for secure credential handling, emphasizing that credential storage should always involve encryption and proper access controls rather than simple cleartext storage mechanisms. Additionally, organizations should consider implementing network monitoring and access control measures to detect unauthorized proxy authentication attempts and establish comprehensive incident response procedures for credential compromise scenarios.