usd-2018-0017 | Lexware Professional 2017/17.02

Advisory ID: usd-2018-0017
CVE Number: N/A
Affected Product: Lexware Professional 2017
Affected Version: 17.02
Vulnerability Type: Broken Authentication
Security Risk: Critical
Vendor URLL: https://shop.lexware.de/reisekosten-abrechnung
Vendor Status: Fixed

Description

Access control enforces policy such that users cannot act outside of their intended permissions. Failures typically lead to unauthorized information disclosure, modification or destruction of all data, or performing a business function outside of the limits of the user.

The vulnerability that merits mention, is the hardcoded encryption/decryption key used in the Lexware client. At a glance, the process setup works by encrypting the user delivered password by the client and delivering the same to the database and the decrypting works vice-versa, wherein encrypted password is fetched from the database and decrypted by the Lexware client. Even though this might appear a sound process on a first look, the presence of decrypting algorithm implies an alternate method to obtain user passwords. A simplified option would be to use the client’s decryption feature to do the work.

For example, in the user management options, the decrypted password is hidden by the client with a dot option. This highly simplified method can be easily bypassed with existing tools.

Proof of Concept 

A sample screenshot is provided to enhance the ease of understanding. It shows the decrypted administrator password.