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Code sign certificates assure users that any software is not maliciously altered. But what happens if a malicious program uses a legitimately issued certificate?

Last week, Adobe released an advisory warning users of malicious utilities carrying legitimate Adobe certificates. According to the advisory, they are currently looking into certain utilities carrying legitimate Adobe-issued certificates. To immediately address this misuse, the software vendor is expected to revoke certificates on October 4 for all software code signed after July 10 2012.

Trend Micro researchers were able to gather and analyze these utilities. Below are our corresponding detections:

• PwDump7.exe (detected as HTKL_PWDUMP)
• myGeeksmail.dll (detected as TROJ_AGENT.MGSM)

Based on our analysis, HTKL_PWDUMP extracts hash values from binary SAM and SYSTEM files in the file system, which may result to unauthorized Windows passwords retrieval, and is a well known tool. On the other hand, TROJ_AGENT.MGSM redirects traffic on a web server.

Misused Certificates As Effective Social Engineering Tools

The real risk of malware using valid certificates is that attackers may use this as a social engineering tactic. Given these are designed to assure users that programs are legitimate and not modified, users are likely to trust and execute malicious programs with such certificates. Misusing certificates was also found on certain targeted attacks. If you may recall, specific components of the notorious FLAME attack, which targeted Iran and other predetermined countries, were found using Microsoft-issued certificates.

Adobe clarifies that this issue does not affect systems with genuine Adobe software and currently does not present a security risk to general consumers. However, a small number of users, in particular IT administrators, may need to perform certain corrective measures. To read more about Adobe’s course of action and advisory, you may refer to Adobe‘s blog entry.

Trend Micro Smart Protection Network™ protects users from this threat by detecting and deleting these utilities.