Did Hackers Peek into Microsoft’s Source Code? Insights from the SolarWinds Attack

Incident Overview

On a Thursday, a hacker group infiltrated Microsoft’s internal network via the SolarWinds platform, obtaining internal accounts that allowed them to view Microsoft’s source‑code repositories.

Microsoft stated that the compromised accounts only had read‑only permissions, so no code changes were made.

Days later, reports emerged that the same attackers had compromised SolarWinds itself, inserting malicious code into Orion updates that were distributed to numerous companies and government agencies worldwide.

Microsoft’s Response

Microsoft posted on its security response center blog that, although the attackers examined some source code, they never reached production systems, user data, or achieved their intended objectives.

The company emphasized that its internal source‑code practices follow open‑source best practices and that the source code remains transparent within Microsoft.

Microsoft also clarified that it does not rely on source‑code secrecy for product security; the threat model focuses on attacker knowledge, and merely viewing source code does not necessarily increase risk.

Broader Implications

Source code is one of the most confidential assets of a software company. Even read‑only access can provide attackers with valuable insights that could be used to undermine products or services.

Ronen Slavin, CTO of CyCode, a source‑code protection firm, warned that the breach could be a prelude to larger attacks, noting that Microsoft’s extensive product portfolio—from Windows to Yammer and Sway—means many repositories could be of interest.

Microsoft’s investigation has found no evidence of access to production systems or user data, and no signs of ongoing attacks have been detected.

Recent years have seen large‑scale leaks of Microsoft products, such as Windows 10, Windows XP, and Windows 2000 source code, underscoring the ongoing security challenges.