CWE-1330: Remanent Data Readable after Memory Erase

How it's found

Remanent Data Readable after Memory Erase is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.

Data remanence occurs when stored, memory content is not fully lost after a memory-clear or -erase operation. Confidential memory contents can still be readable through data remanence in the hardware. Data remanence can occur because of performance optimization or memory organization during 'clear' or 'erase' operations, like a design that allows the memory-organization metadata (e.g., file pointers) to be erased without erasing the actual memory content. To protect against this weakness, memory devices will often support different commands for optimized memory erase and explicit secure erase. Data remanence can also happen because of the physical properties of memory circuits in use. For example, static, random-access-memory (SRAM) and dynamic, random-access-memory (DRAM) data retention is based on the charge retained in the memory cell, which depends on factors such as power supply, refresh rates, and temperature. Other than explicit erase commands, self-encrypting, secure-memory devices can also support secure erase through cryptographic erase commands. In such designs, only the decryption keys for encrypted data stored on the device are erased. That is, the stored data are always remnant in the media after a cryptographic erase. However, only the encrypted data can be extracted. Thus, protection against data recovery in such designs relies on the strength of the encryption algorithm.

Consequences

• Modify Memory, Read Memory: Confidential data are readable to untrusted agent.

Mitigations

• Architecture and Design: Support for secure-erase commands that apply multiple cycles of overwriting memory with known patterns and of erasing actual content. Support for cryptographic erase in self-encrypting, memory devices. External, physical tools to erase memory such as ultraviolet-rays-based erase of Electrically erasable, programmable, read-only memory (EEPROM). Physical destruction of media device. This is done for repurposed or scrapped devices that are no longer in use.

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Base weakness
  CWE-1301: Insufficient or Incomplete Data Removal within Hardware Component