Skype security flaw 'ignored' by Microsoft could allow hackers to gain access to users' computers

A fix will instead land in a newer version of the product rather than a dedicated security update

A security bug has been uncovered in Skype via its update process which could allow hackers to gain access to a user's computer.

If exploited by an attacker, the flaw could give a local unprivileged user full access to the system level rights, a security expert over at Seclists.org has warned, giving access to every part of the operating system.

Advertisement - Article continues below

"Once installed, Skype uses its own proprietary update mechanism instead of Windows/Microsoft Update," said security researcher Stefan Kanthak. "[Because] Skype periodically runs '%ProgramFiles%\Skype\Updater\Updater.exe' under the SYSTEM account, when an update is available, [the] Updater.exe copies/extracts another executable as '%SystemRoot%\Temp\SKY

Kanthak explains that its this executable is vulnerable to DLL hijacking as it loads at least a DLL file called 'UXTheme.dll' from its application directory named '%SystemRoot%\Temp\' instead of from the Windows' system directory.

"An unprivileged (local) user who is able to place UXTheme.dll or any of the other DLLs loaded by the vulnerable executable in '%SystemRoot%\Temp\' gains escalation of privilege to the SYSTEM account," he added.

While Microsoft, who owns the video-calling service, has published plenty advice and guidance on how to avoid this error, Kanthak says the tech giant's own developers seem to be "ignoring it".

Advertisement
Advertisement - Article continues below

The security expert informed Microsoft of the bug in September, but according to the Seclists' reported timeline of the bug, a fix will instead land in a newer version of the product rather than a dedicated security update.

Advertisement - Article continues below

"The [Microsoft] engineers provided me with an update on this case," he said. "They've reviewed the code and were able to reproduce the issue, but have determined that the fix will be implemented in a newer version of the product rather than a security update.

"The team is planning on shipping a newer version of the client, and this current version will slowly be deprecated," he added. "The installer would need a large code revision to prevent DLL injection, but all resources have been put toward development of the new client."

With no further action made by Microsoft since, Kanthak published the report on Friday as a warning to Skype users.

Featured Resources

Preparing for long-term remote working after COVID-19

Learn how to safely and securely enable your remote workforce

Download now

Cloud vs on-premise storage: What’s right for you?

Key considerations driving document storage decisions for businesses

Download now

Staying ahead of the game in the world of data

Create successful marketing campaigns by understanding your customers better

Download now

Transforming productivity

Solutions that facilitate work at full speed

Download now
Advertisement

Recommended

Visit/security/ransomware/356292/university-of-california-gets-fleeced-by-hackers-for-114-million
ransomware

University of California gets fleeced by hackers for $1.14 million

30 Jun 2020
Visit/security/cyber-security/356289/australia-announces-135b-investment-in-cybersecurity
cyber security

Australia announces $1.35 billion investment in cyber security

30 Jun 2020
Visit/cloud/cloud-security/356288/csa-and-issa-form-cybersecurity-partnership
cloud security

CSA and ISSA form cyber security partnership

30 Jun 2020
Visit/business/policy-legislation/356215/senators-propose-a-bill-aimed-at-ending-warrant-proof-encryption
Policy & legislation

Senators propose a bill aimed at ending warrant-proof encryption

24 Jun 2020

Most Popular

Visit/business-strategy/careers-training/356422/ibm-job-ad-calls-for-12-year-experience-with-6-year-old
Careers & training

IBM job ad calls for 12-years of experience with six-year-old Kubernetes

13 Jul 2020
Visit/business/business-operations/356395/nvidia-overtakes-intel-as-most-valuable-us-chipmaker
Business operations

Nvidia overtakes Intel as most valuable US chipmaker

9 Jul 2020
Visit/security/cyber-attacks/356417/trump-confirms-cyber-attacks-on-russia-election-trolls
cyber attacks

Trump confirms US cyber attack on Russia election trolls

13 Jul 2020