1. 概要
2016年，AmEx 成立了 RAT （Rewards Abuse Team）部门，专门严打各种不合他们的规矩拿点数的活动。当时，我们就有专文介绍：这里。
到现在，3年过去了，这个 RAT 的活动也越发被大家了解，甚至一些了解 RAT 运作的人也偶尔在各个信用卡博客论坛发言，让大家对于 RAT 主要逮的活动更加明了。
本文就和大家聊一聊最近一点新的小道（非官方）消息。当然啦，AmEx 官方肯定是不会告诉我们他们在做什么和要做什么的，只是有人在英文博客上的留言，但是感觉这个留言还是有一定道理的。
2. 起因
事情的起因是最近 AmEx 对于过去1年内self-refer获得点数收回，紧接着又有一些人被 AmEx 杀全家（关所有卡）：文章在这里。Reddit 上有人做了调查和分析（这里），认为主要触发原因可能是
- Self refer 点数收回
- 拥有超过1张同样的 AmEx 卡（比如，有人有2张甚至3张金卡 Gold）
RAT 应该是通过这些因素来筛选持卡人，如果他们觉得风险较高或者撸得太过分，就会关卡。
3. 可怕之处
杀全家（关所有卡）其实别的银行更喜欢，比如Chase，各种原因杀全家：专文在这里。
但是 AmEx 杀全家的可怕之处是他家这一行为颠覆了大家对他家的认知。以前，如果大家有不合他家喜好的行为，AmEx 通常先对于持卡人进行一次 Financial Review，如果收入可以通过他家的 Financial Review，所有卡都可以保留并正常使用。对于 AmEx Financial Review，我们有专文（这里）。
也就是说，历史上，AmEx 很少直接杀全家（当然，也有个别比较过分的被不经过 Financial Review 直接杀全家，但是非常非常少见），都是 Financial Review 猫捉老鼠玩一玩，过了就不杀，只有过不了 Financial Review 才杀全家。但是这次，AmEx 对于这些可能违反了他们一些条款的持卡人，不再进行 Financial Review，直接杀全家。也就预示着，被 RAT 盯上的持卡人，是有可能不进行 Financial Review 就直接杀全家的。
可怕之处就在此了：Financial Review Team 可怕，但是还是讲道理的，只要有美国的税表，申请卡的时候收入和税表基本一致，就几乎肯定可以通过 Financial Review；但是 RAT 完全不给持卡人机会，直接就关所有卡了，持卡人连申诉的权利也不会有。
为了避免被 AmEx RAT 直接杀全家，大家不得不了解一下 RAT 究竟在干什么，他们根据那些不合适行为杀全家。
4. 新消息（非官方）
在 DoC AmEx 杀全家文的回复里，有个ID是 RAT Poison 的读者回复了一些他知道的关于 RAT 的信息。虽然我们不清楚这个人是不是和 AmEx 相关的人，但是他说的确实有一定道理和借鉴意义。RAT Poison 的回复在这里，为了保留一些这个回复做参考，我们把他的回复复制在这里：
- I won’t say why or how, but I have insider info from RAT on what’s behind all this. This shutdown is part of a series of upcoming shutdowns. This week’s was a beta test for a new machine learning model specifically designed to target churning activity through unsupervised learning. Amex data scientists are improving an evolving neural network model that identifies churning behavior as it happens, and then assigns risk scores that factor in to anti bust-out or fraud scores. They’re treated the same, those all have different scores but their values affect your overall risk/reward score for Amex. If that overall score reaches a certain threshold (which they’re still experimenting with what exactly it will be), you will get shut down. What they’re doing is based on the same ML models that are used at Amex for AML and fraud prevention. The shutdowns will happen in small waves because one giant hit would be a massive drain on resources and disruption to their overall business, including drawing negative public attention outside of the churning community. That would scare people who are profitable but think they’re winning. They are also incrementing shutdown waves because of the resource usage it takes to identify accounts and assign a score based on the new indicated risk factors. When shutdowns are triggered, they begin combing through the new dataset. Right now, the model only looks back two years.
- The clawbacks on self-referrals were a pilot program to this week’s events, not an entirety separate event. The same model that identified self-referrers was used for these shutdowns.
- I’ll report back when I hear more info.
- Also, I should add that if you had self-referrals clawed back, you’re already in the main data set. Those who were hit by the clawback were flagged as the highest priority for the model to comb through because of the strong correlation to proven churning/gaming behavior. Self-referrals were like a litmus test for who will be the low-hanging fruit for them to cut. As they tune the model to identify more positive activity correlations with churning, it will get more specific. Combing through level 3 data will become more prevalent in identifying churners, especially true if you have transactions from GCM and other obvious sites in your transaction history. If you were hit in the clawback but weren’t shut down this time, be cautious that you’re in their crosshairs. From what I’ve learned about the model, the inferred course of action here to avoid a shutdown is to not do anything with Amex except organic spend on your existing cards. Don’t carry a balance, no more MS, and no new cards. Keep in mind that the anti-churning model is fundamentally based on the neural architecture of their anti-fraud model.
- PS I’ve read many comments loosly speculating about what RAT is. RAT isn’t a bunch of guys in India who are manually combing through the accounts with high MR balances, or checking referral sources for validity, etc.. This isn’t true. “RAT” is two data science and machine learning engineers in Phoenix who transitioned from the Amex fraud prevention team. There are two other engineers who have shared responsibilities with RAT and other anti-fraud teams.
- The Hilton Aspire no AF link had absolutely nothing to do with these shutdowns. It’s a pure coincidence. The portfolio of recommended accounts to be shut down was sent off for approval more than a week ago. RAT doesn’t shut down accounts. They provide tranches of customer accounts suspected of abuse – along with correlating data. Those tranches go to evaluation from non-engineering management; who are the decision makers on shutting down a tranch of accounts or enacting other penalties. This is new to them and it’s somewhat uncharted territory, the speculations on here and on Reddit that they’re winging it are accurate. Their plan is to cut losses and effectively disable Amex churning first, then deal with the fallout afterwards. They’re legally within their rights so shutdown approvals are not made on a legal basis.
他的回复里有几个要点，我们总结一下：
- AmEx RAT 正在使用神经网络机器学习模型对 AmEx 掌握的大数据进行分析，从而抓出 Abuse Rewards 的人。
- AmEx RAT 的想法是，使用他们的模型给每个持卡人一个风险（risk，拿了人家多少点数）和收益（reward，给 AmEx 贡献了多少收入）评分，如果这个评分高于某个阈值，RAT就会杀全家；当然，RAT 仍然在调试模型，找出合适的阈值：他也不想误杀了给 AmEx 带来收益比较高的持卡人。
- 现在的Self refer是第一批抓出来的，因为 Self refer 和 churning 有比较直观的联系。
- 未来，RAT 会优化他们的机器学习模型，一波一波的抓出 Abuse Rewards/churning 的持卡人，直接杀全家。
- 被因为 Self refer 收回点数的持卡人要尤其注意，这些持卡人已经在 RAT 的重点观察名单里，如果再犯别的，就有可能被杀全家。
- 近期的未来，RAT 会在模型里加入 Level 3 data（就是持卡人在商店每笔交易的具体内容，包括买了啥东西），对于买 Gift Card 的，是重点观察对象。
- 最近的 Hilton Aspire 免第一年年费链接和杀全家没关系（我们的文在这里）。
- 有一点好的地方：RAT 的模型只查看过去2年的数据，持卡人在2年之前的行为模型就不考虑了。
他建议的几点安全行为：
- 不要申新卡。
- 不要制造消费（Manufacture Spending），就是不要买现金等价物，Visa Gift Card 之类的，不要在 GiftCardMall 之类的网站消费。
- 每月付清账单。
5. 我们应该怎么做来避免被 AmEx RAT 杀全家
综合上面的信息，我们这样做也许可以帮助避免被杀全家
- 一定不要 Self Refer。
- 之前申请过的卡，一定不要再次申请。
- 不太现实的一点：不要申新卡。也许可以折中一下，如果持有若干张 AmEx 卡以后，尽量少申新卡。
- 不要制造消费（Manufacture Spending），就是不要买现金等价物，Visa Gift Card 之类的，不要在 GiftCardMall 之类的网站消费。
- 每月付清账单。
6. 总结
AmEx 也加入了直接杀全家的银行大家庭，以后申请和使用 AmEx 卡大家都要再更当心一些，不要惹了 AmEx RAT。
注明：本文主要目的是让更多中文读者了解 AmEx RAT，规避风险。本文参考了 FrequentMiler ，他们更早注意到RAT Poison的回复并分析，在此致谢！