Why S3 Buckets don't beat MFT Systems
- David Heath
- Jul 1
- 3 min read
Why Managed File Transfer Beats “Just Drop It in S3” for B2B Exchanges
Object-storage services such as Amazon S3 are terrific for inexpensive, durable cloud storage, so it is tempting to let trading partners push and pull payloads there directly. Yet the moment those partners start writing into your buckets you lose the very controls that make regulated, large-scale data exchange safe and auditable. Managed File Transfer (MFT) platforms exist to close that gap, and the difference matters more today than ever.
Governance, visibility and non-repudiation by design
An MFT gateway is built around authentication, encryption in motion and at rest, automatic checksum verification, granular access policies and a complete audit trail of every transaction. These capabilities allow organisations to prove compliance with mandates such as PCI-DSS, HIPAA and GDPR, recover quickly from failures and enforce service-level agreements without manual intervention . By comparison, a partner writing to your S3 bucket authenticates only once (via IAM credentials or a pre-signed URL); after that the cloud platform simply stores objects. The cloud console may tell you that something was uploaded, but it will not prove who touched the data, whether it completed successfully, or whether a checksum changed en route.
Inline malware inspection in the DMZ
IBM Sterling Secure Proxy (SSP) sits in the demilitarised zone, terminates external sessions and streams each file through an ICAP-connected antivirus engine in memory, without ever writing the payload to disk. If malware is detected the transfer is aborted and logged before the file reaches the trusted network . Direct S3 uploads cannot offer that safeguard. Amazon GuardDuty Malware Protection can scan an object after it lands, but it does so only once, cannot be invoked just before download and cannot prevent the initial write to your bucket . In other words, an infected file can reside in your cloud account for hours—or forever—before anyone knows.
Data-loss-prevention that can
block
exfiltration
Sterling Secure Proxy also supports ICAP integration with enterprise DLP engines. During an outbound transfer it inspects the stream in flight; if a partner or compromised internal user tries to send credit-card numbers or other sensitive content, SSP can stop the transmission at the perimeter . Amazon Macie or GuardDuty can detect sensitive data in S3, but they work asynchronously and only generate findings that an administrator must later remediate; they do not block the violation in real time . That delay is unacceptable when your brand and regulatory posture depend on keeping data from ever leaking out.
Operational reliability and partner experience
Because MFT platforms negotiate protocols such as SFTP, FTPS, AS2 and Connect:Direct, partners do not need to learn cloud APIs. Transfers resume automatically after network glitches, large payloads can be checkpoint-restarted, and administrators receive proactive alerts if an SLA is at risk . With direct object-storage writes the burden shifts to each trading partner to build retry logic, encryption, logging and notification—fragmenting your ecosystem and multiplying failure modes.
The bottom line
Letting external parties write straight into your cloud buckets may seem simple, but simplicity fades the first time a malicious payload sneaks through or a hacked credential starts siphoning customer data. An MFT layer such as IBM Sterling Secure Proxy restores the perimeter: it authenticates every connection, inspects every byte for malware, enforces DLP rules before data exits and records an immutable audit trail. That combination of security, compliance and operational visibility is unattainable when partners interact with raw object storage alone—and that is why serious B2B programmes keep MFT front and centre.
By David Heath
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