Trend Micro recently patched a couple of DLL hijacking vulnerabilities in Password Manager that could allow malicious actors to escalate privileges, make their malware persistent, and to load and execute their payloads via a signed service.
A security bulletin published by Trend Micro this week informs customers that an update released for its Password Manager 5.0, including the standalone version and the one shipped as an optional component of Premium Security and Maximum Security, fixes two DLL hijacking vulnerabilities.
The flaws, tracked as CVE-2019-14684 and CVE-2019-14687, were reported by researchers at SafeBreach and Infiniti Team – VinCSS. The weaknesses are similar, but they target different DLLs.
SafeBreach published a blog post on Wednesday disclosing the technical details of the vulnerability found by its researchers.
According to SafeBreach, the Trend Micro Password Manager’s Central Console Service executes a signed process, PwmSvc.exe, with SYSTEM privileges. This service then loads the Trend Micro Whitelist Module library (tmwlutil.dll), which in turn attempts to load another DLL file, tmtap.dll.
The problem is that this DLL is not loaded safely from an absolute path and the application does not verify that the loaded DLL is signed.
An attacker or process that has administrative privileges on the targeted device can modify the system PATH variable to include a folder they have control over. They can then place a malicious DLL named tmtap.dll in that folder, and it will get executed with SYSTEM privileges whenever Password Manager is started.
An attacker can exploit the vulnerability to have their malicious payloads loaded and executed by a signed process, which can be used to bypass application whitelisting mechanisms. It can also be used as a persistence mechanism as the malicious DLL will get executed every time the service is restarted.
An attacker with privileges limited to accessing only certain files and data can exploit the vulnerability to elevate privileges to SYSTEM, giving them complete access to the device.
The flaw was reported to Trend Micro on July 23 and it was patched just one week later, despite the fact that it has only been assigned a “medium severity” rating.