Following the reports last week using the Windows Global Device ID (GDID) in tracking a malware operators behavior, here is a comprehensive write-up about what goes into the GDID and how it is used. It’s worth noting that the GDID itself was not used to catch the malware operator, however once a suspect was identified, the GDID was used to correlate behavior across various Microsoft products on the Internet.
The GDID is generated and assigned during a Windows install, but a re-install of Windows will generate a new GDID. Developer [SmtimesIWndr] tracks the generation and tracking of the GDID through the various Windows libraries and services, identifying where it appears to be created and how it is passed to other services like Azure.
Worth noting is your GDID is a unique, personally identifiable piece of information; if you go exploring and extract it from your Windows install, be sure to keep it private!
LAME mp3 updates
Those of us who were around for the dawn of MP3 files may remember the LAME encoder and library. After almost 10 years, there is a new LAME release.
Notably, this includes two security fixes, one for a stack buffer overflow based on malicious input to the Blade encoder, and an integer underflow in the AIFF header parser. Both of the fixed bugs feel very old-school, which seems appropriate given the age of the library and most of the related code.
Buffer overflows impacting the stack are some of the simplest and most direct forms of vulnerabilities, where it is possible to write past the end of a buffer and control how the function returns and instead execute arbitrary code. Integer under-flows, similarly, impact memory management; usually caused by allowing a variable that stores the size of a buffer to go negative. Since sizes are typically unsigned positive numbers, a negative is interpreted as an enormous positive number, writing past the proper buffer length.
Despite the new findings, the LAME codebase has been extremely resilient over the years, and considering the number of programs that likely still use LAME under the covers to process audio, seeing the project wake up with security fixes is great news.
Recovering Passwords from BIOS
Researchers have found a vulnerability in Dell BIOS code that allows extraction of the administrator password from the BIOS flash chips, either with physical access via a flash programmer, or via administrator or root level access to the operating system and reading the contents of the flash chip.
Dell used a 20 byte key to encrypt a 32 byte password field: for any admin password of 12 characters or fewer, the password is stored in completely plaintext. For longer passwords, characters beyond the first 12 are encrypted – but the random bytes are computed from the first character of the password mixed with fixed device data, yielding only 256 possible encryption seeds for the remaining bytes.
Using the BIOS admin password for evil requires local access, so the attack surface is small, however as the researchers note it controls the boot order and may allow an attacker with physical access to then boot an unsigned OS or bypass full-disk encryption, so it’s serious.
