April 2, 2013 By Dancho Danchev

Spamvertised ‘Re: Changelog as promised’ themed emails lead to malware

We have recently intercepted a malicious spam campaign, that’s attempting to trick users into thinking that they’ve received a non-existent “changelog.” Once gullible and socially engineered users execute the malicious attachment, their PCs automatically become part of the botnet operated by the cybercriminal/gang of cybercriminals.

More details:

Sample screenshot of the spamvertised email:

Email_Spam_Malware_Malicious_Software_Social_Engineering_Changelog

Detection rate for the malicious attachment:
MD5: e01ea945b8d055c5c115ab58749ac502 – detected by 23 out of 46 antivirus scanners as Worm:Win32/Cridex.E.

Upon execution, the sample creates the following processess on the affected hosts:
C:WINDOWSsystem32cmd.exe” /c “C:DOCUME~1<USER>~1LOCALS~1Tempexp1.tmp.bat
C:Documents and Settings<USER>Application DataKB00927107.exe

The following Registry Keys:
HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCFBDC89D4
HKEY_CURRENT_USERSoftwareMicrosoftWindows NTS25BC2D7B

The following Registry Values:
[HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun] -> KB00121600.exe = “”%AppData%KB00121600.exe””

As well as the following Mutexes:
LocalXMM000003F0
LocalXMM00000200
LocalXMM000003F8
LocalXMI000003F8
LocalXMRFB119394
LocalXMM000005E4
LocalXMI000005E4
LocalXMM0000009C
LocalXMI0000009C
LocalXMM000000C8
LocalXMI000000C8

It then phones back to hxxp://85.214.143.90:8080/DPNilBA/ue1elBAAAA/tlSHAAAAA/ and to hxxp://91.121.90.92:8080/AJtw/UCyqrDAA/Ud+asDAA/

We’ve already seen the same C&C (85.214.143.90) used in a previously profiled malicious campaign:

Users are advised to avoid interacting with these emails, and to be extra vigilant for similar social engineering driven malicious campaigns.

Webroot SecureAnywhere users are proactively protected from this threat.

You can find more about Dancho Danchev at his LinkedIn Profile. You can also follow him on  Twitter.

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