Skip to main content
Commerce Security Authority
Category: Data Protection Methods

Volatile Memory

Simply put

Volatile memory is a type of computer memory that only holds data while the device has power. When the power is turned off or lost, the stored information disappears. This contrasts with non-volatile memory, which retains its contents without a continuous power supply.

Formal definition

Volatile memory is computer memory that requires a continuous supply of power to maintain the stored information and loses its content when power is turned off or lost. It is commonly used for temporary storage of data during active processing. In a payment security context, practitioners should note that sensitive authentication data may transiently exist in volatile memory during authorization; the treatment and protection of data in volatile memory should be evaluated against the current published PCI DSS requirements rather than assumed, since requirement numbering and wording differ between versions.

Why it matters

Volatile memory matters in payment security because sensitive authentication data — such as full track data, the card verification value (CAV2/CVC2/CVV2/CID), and PIN blocks — may transiently exist in volatile memory during the authorization process. While PCI DSS prohibits storing sensitive authentication data after authorization even when encrypted, data that lives only in volatile memory during active processing is treated differently from data written to persistent storage. Because volatile memory loses its contents when power is removed, it is not persistent storage in the conventional sense, but it can still be a target for attackers while a system is running.

The distinction is operationally important: memory-scraping malware and forensic memory capture techniques can extract data from volatile memory while a device is powered and processing. This means that the transient presence of cardholder data or sensitive authentication data in volatile memory is a legitimate area of risk analysis, not something that can be dismissed simply because the data is not written to disk. How this data is protected while resident in volatile memory, and how it is cleared after use, should be evaluated against the current published PCI DSS requirements rather than assumed.

Practitioners should confirm the applicable controls against the current version of the standard, since requirement numbering and wording differ between PCI DSS versions. The label 'volatile' describes a hardware behavior — loss of contents on power loss — and does not by itself establish that data in such memory is out of scope or adequately protected.

Who it's relevant to

Security Engineers
Engineers designing payment applications need to account for how sensitive authentication data and cardholder data move through volatile memory during authorization, including how such data is protected while resident and how it is cleared after use. Because volatile memory can be a target for memory-scraping techniques while a system is powered, its transient nature should not be assumed to place data out of scope.
Compliance Officers and QSAs
Those validating PCI DSS compliance should evaluate the handling of data in volatile memory against the current published standard rather than assuming a fixed treatment. Requirement numbering and wording differ between PCI DSS versions, so the applicable controls for transient data in memory should be confirmed against the specific version in scope for the assessment.
Payment Processors and Acquirers
Organizations processing authorizations should understand that sensitive authentication data may exist transiently in volatile memory during the authorization flow. This informs how systems are hardened against memory-based attacks and how the distinction between persistent storage and transient processing memory is documented in their environment.

Inside Volatile Memory

Transient data storage
Volatile memory (such as RAM) holds data only while a device is powered; contents are lost when power is removed, distinguishing it from non-volatile storage like disks or flash.
In-flight cardholder data
During processing, cardholder data such as the PAN, cardholder name, expiration date, and service code may transiently reside in volatile memory before, during, or after authorization.
In-flight sensitive authentication data
Sensitive authentication data (full track data, CAV2/CVC2/CVV2/CID, and PINs or PIN blocks) may also pass through volatile memory during authorization. This data must not be stored after authorization, even when encrypted, but its transient presence in memory during processing is a distinct condition that requires protection.
Memory-scraping attack surface
Malware, notably RAM-scraping variants, can target data while it is temporarily unencrypted in volatile memory, making memory a relevant consideration for endpoint and application security controls.
Scope and control relevance
System components that process cardholder data may bring volatile memory contents into consideration for security controls; whether and how this affects PCI DSS scope depends on the environment, implementation, and validation rather than the term alone. Confirm applicable requirements against the current published standard.

Common questions

Answers to the questions practitioners most commonly ask about Volatile Memory.

Is data in volatile memory out of PCI DSS scope because it is not persistently stored?
No. The fact that data resides in volatile memory (such as RAM) rather than on persistent storage does not automatically place it out of PCI DSS scope. Cardholder data and sensitive authentication data are subject to applicable controls while being processed, including while held in memory. The prohibition on storing sensitive authentication data after authorization concerns retention, but data present in memory during processing still falls within the systems and processes that must be assessed. Scope depends on how the data is handled, protected, and validated, not on the storage medium's volatility. Confirm the specific requirements against the current published standard.
Does data in volatile memory disappear safely on its own, so it does not need to be protected?
Not reliably. While volatile memory generally loses its contents when power is removed, data can persist in memory for unpredictable periods during operation, may be written to swap or paging files, or may be captured in crash dumps and memory images. Memory-scraping malware specifically targets data in RAM during processing. Treating volatile memory as inherently self-clearing can create a false sense of security. Controls should address how sensitive data is handled, cleared, and protected in memory, rather than assuming volatility alone provides protection.
How can memory-scraping malware capture cardholder data from volatile memory?
Memory-scraping malware runs on a system that processes payment data and reads the process memory where cardholder data or sensitive authentication data may briefly appear in cleartext during handling, for example between decryption and re-encryption. Reducing this exposure typically involves minimizing the time and locations where such data appears in memory, applying encryption or point-to-point approaches so cleartext data is limited, hardening and monitoring systems, and controlling what code can run. These measures help reduce risk but do not by themselves eliminate it, and their effect on scope depends on implementation and validation.
What practices help reduce the exposure of sensitive data in volatile memory?
Practices that may help reduce exposure include minimizing how long and where cleartext data resides in memory, overwriting or clearing memory buffers promptly after use where feasible, disabling or restricting memory dumps and swap files that could capture sensitive data, and limiting which processes can access payment data. Approaches such as P2PE, as governed by the PCI P2PE standard, and tokenization can reduce the amount of cleartext data that reaches or lingers in memory, though their effect on scope depends on implementation and validation rather than the label alone.
Do crash dumps and swap files need to be considered when protecting memory-resident data?
Yes, they warrant attention. Data that exists in volatile memory can be written to disk through crash dumps, core dumps, hibernation files, or swap and paging files, which can effectively create persistent copies of data that was intended to remain transient. Where sensitive authentication data is involved, such persistence would conflict with the requirement not to retain that data after authorization. Reviewing and controlling these mechanisms is part of assessing how data in memory is handled; verify applicable requirements against the current published standard.
How should volatile memory handling be reflected when defining assessment scope and data flows?
Systems that process payment data in memory should be represented in data-flow diagrams and scope documentation so that assessors can see where cardholder data and sensitive authentication data appear during processing, including in memory. This helps identify the systems, applications, and controls that must be evaluated. Because scope is determined by how data is handled and validated rather than by the storage medium, documenting memory-resident processing supports accurate scoping. Confirm the specific documentation and control expectations against the current published standard.

Common misconceptions

Data in volatile memory is safe because it is temporary and disappears when power is cut.
While volatile memory does not persist after power loss, data can remain resident during operation long enough to be captured by memory-scraping malware or debugging tools while the system is running. Its transient nature does not by itself provide protection.
The prohibition on storing sensitive authentication data after authorization does not apply to volatile memory, so anything in RAM is acceptable.
Sensitive authentication data must not be retained after authorization. Transient presence in volatile memory during processing is a different condition from post-authorization storage, but it still warrants protective controls; it does not create an exemption from the underlying requirement.
Encrypting stored data means memory-resident data is automatically protected.
Data typically must be decrypted to be processed, so it may exist in cleartext in volatile memory during processing regardless of encryption at rest. Encryption of stored data does not guarantee that in-memory data is protected.

Best practices

Minimize the time cardholder data and sensitive authentication data remain in volatile memory, and clear or overwrite memory buffers as soon as the data is no longer needed.
Deploy and maintain anti-malware and endpoint controls capable of helping detect memory-scraping techniques, while recognizing that detection tools have false-positive and false-negative trade-offs.
Ensure sensitive authentication data is not written from memory to any persistent store after authorization, and validate that logs, crash dumps, and temporary files do not inadvertently capture it.
Restrict administrative, debugging, and memory-inspection access to systems that process cardholder data, and monitor for unauthorized use of such tools.
Where supported, use point-to-point encryption or tokenization approaches to reduce the exposure of cleartext data in memory, confirming their scope impact through proper validation rather than assuming it from the label.
Confirm applicable controls and requirement wording against the current published PCI DSS version, since numbering and phrasing differ between versions.