Feeds

Reg readers crack case of the $23 quadrillion overcharge

<empty field> + binhex = Visa FAIL

HP ProLiant Gen8: Integrated lifecycle automation

It seems an empty amount field is the culprit in the programming glitch that caused some 13,000 holders of prepaid Visa cards to receive warnings that their accounts were overdrawn by more than $23 quadrillion.

At least, that's the theory advanced by several Register readers, who posit an 8-byte blank field was converted to binary format, giving it a value of 0x2020202020202020. Converted to an integer decimal, that translates to 2,314,885,530,818,453,536, an amount that's not far off from the number of cents these customers were charged for a wide variety of purchases.

To recap from Wednesday, Visa sent about 13,000 customers statements claiming their accounts were overdrawn because of a charge for exactly $23,148,855,308,184,500.00. The company quickly identified the problem, which it blamed on a "temporary programming error," and corrected the charges.

Of course, Visa didn't detail the programming error, and that made some of you curious. In a comment titled "Visa deserves glitchslapping?," an anonymous coward pointed out that the incorrect charges, which applied to purchases for cigarettes, gasoline, and sundry other items and services, came to exactly 2,314,885,530,818,450,000 cents, which when converted to binhex comes to 2020202020201250.

"It looks to me like somebody blank-filled a field, plopped the actual charged amount into the end (hex 1250, decimal 4688, likely amount $46.88), and then interpreted the entire field as a hex number," AC wrote. "If so, this is the kind of bug that would have been caught in even the most cursory testing, in which case the 'technical glitch' Visa talks about was not really in the software--bugs happen--but in their own shoddy procedures that allowed untested software to go live."

This still doesn't explain how 13,000 people could all be charged precisely the same amount for purchases whose real-world value were vastly different. Reg reader Stuart McConnachie, who also forwarded the binhex theory, guesses the identical overcharge is the result of a rounding error. When converting to a real number, only the first 15 digits were included, he said. The remainder were converted to zero.

While several of you were astonished that such an elementary mistake could have made it into Visa's live production, at least one reader was impressed that the company's computing system was robust enough to handle the error without crashing.

"I'm impressed at their systems' coders who wrote a system capable of coping with figures like that, and not falling over!" NogginTheNog wrote. "I mean I've heard of inflation-proofing, but really..." ®

The Power of One eBook: Top reasons to choose HP BladeSystem

More from The Register

next story
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Apple fanbois SCREAM as update BRICKS their Macbook Airs
Ragegasm spills over as firmware upgrade kills machines
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Captain Kirk sets phaser to SLAUGHTER after trying new Facebook app
William Shatner less-than-impressed by Zuck's celebrity-only app
Do YOU work at Microsoft? Um. Are you SURE about that?
Nokia and marketing types first to get the bullet, says report
Microsoft takes on Chromebook with low-cost Windows laptops
Redmond's chief salesman: We're taking 'hard' decisions
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.