CVE-2020-1556: 
vulnerability analysis and mitigation

CVE-2020-1556 is an elevation of privilege vulnerability that exists in the way the Windows WalletService handles objects in memory. The vulnerability was discovered and assigned on November 4, 2019, and was publicly disclosed on August 17, 2020. This vulnerability affects various versions of Microsoft Windows operating systems (NVD).

The vulnerability stems from improper object handling in memory by the Windows WalletService. Specifically, the issue results from the lack of proper locking when performing operations on an object, which can cause a read past the end of an allocated buffer. The vulnerability has received different CVSS severity ratings: a CVSS v3.1 Base Score of 7.8 (HIGH) according to NVD with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, while ZDI assessed it with a CVSS score of 2.5 (AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N) (NVD, ZDI).

An attacker who successfully exploits this vulnerability could execute code with elevated permissions, potentially gaining SYSTEM-level access. The vulnerability can be leveraged in conjunction with other vulnerabilities to escalate privileges on affected systems (NVD, ZDI).

To exploit the vulnerability, a locally authenticated attacker would need to run a specially crafted application. The attacker must first obtain the ability to execute low-privileged code on the target system (NVD).

Microsoft has released a security update that addresses the vulnerability by ensuring the Windows WalletService properly handles objects in memory. Users are advised to apply the security update to affected systems (NVD).