Jaff ransomware gets a makeover, (Wed, May 24th)

Malware News
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Introduction

Since 2017-05-11, a new ransomware named Jaff has been distributed through malicious spam (malspam) from the Necurs botnet. This malspam uses PDF attachments with embedded Word documents containing malicious macros. border-width:2px" />
Shown above: Flow chart for this infection chain.

Prior to Jaff, weve seen waves of malspam using the same PDF attachment/embedded Word doc scheme to push Locky ransomware. Prior to that, this type of malspam was pushing Dridex.

With all the recent news about WannaCry ransomware, people might forget Jaff is an ongoing threat. Worse yet, some people might not know about it at all since its debut about 2 weeks ago. Jaff has already gotten a makeover, so an infected host looks noticeably different now. With that in mind, todays diary reviews a wave of malspam pushing Jaff ransomware from Tuesday 2017-05-23.

The emails

This specific wave of malspam used a fake invoice theme. It started on Tuesday 2017-05-23 as early as 13:22 UTC and lasted until sometime after 20:00 UTC. I collected 20 emails for today border-width:2px" />
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Shown above: Screenshot from one of the emails.

As stated earlier, these emails all have PDF attachments, and each one contains an embedded Word document. border-width:2px" />
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Shown above: The embedded Word document with malicious macros.

The traffic

Follow the entire infection chain, and youll see minimal network traffic compared to other types of malware. The Word macros generate an initial URL to download an encoded Jaff binary, then we see one other URL for post-infection callback from an infected host. The initial HTTP request for Jaff returns an encoded binary thats been XORed with the ASCII string I6cqcYo7wQ. Post-infection traffic merely returns the string Created border-width:2px" />
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Shown above: Alerts on the traffic using Security Onion with Suricata and the EmergingThreats Open ruleset.

The infected Windows host

The encoded binary from this wave of malspam was stored to the users AppData\Local\Temp directory as lodockap8. Then it was decoded and stored as levinsky8.exe in the same directory. border-width:2px" />
Shown above: The users AppData\Local\Temp directory from an infected host on 2017-05-23.

On Tuesday 2017-05-23, Jaff ransomware had a makeover. border-width:2px" />
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Shown above: Desktop of a Windows host infected with a Jaff ransomware sample from 2017-05-23.

Encrypted files had been previously appended with the .jaff file extension. On Tuesday 2017-05-23, encrypted files from my infected host were appended with a .wlu file extension. border-width:2px" />
Shown above: Jaff decryptor from a Windows host infected on 2017-05-23.

Indicators of Compromise (IoCs)

The following are examples of email subject lines and attachment names from Tuesday 2017-05-23:

  • Subject: Invoice(00-5523) -- Attachment name: 68-5182.pdf
  • Subject: Invoice(00-5832) -- Attachment name: 72-6353.pdf
  • Subject: Invoice(08-4031) -- Attachment name: 28-3137.pdf
  • Subject: Invoice(09-5337) -- Attachment name: 98-9897.pdf
  • Subject: Invoice(19-9273) -- Attachment name: 68-6414.pdf
  • Subject: Invoice(23-0458) -- Attachment name: 53-3366.pdf
  • Subject: Invoice(27-7813) -- Attachment name: 95-1750.pdf
  • Subject: Invoice(28-3137) -- Attachment name: 68-4200.pdf
  • Subject: Invoice(53-3366) -- Attachment name: 61-7808.pdf
  • Subject: Invoice(54-9434) -- Attachment name: 78-8672.pdf
  • Subject: Invoice(61-7808) -- Attachment name: 00-5832.pdf
  • Subject: Invoice(68-4200) -- Attachment name: 98-3753.pdf
  • Subject: Invoice(68-5182) -- Attachment name: 54-9434.pdf
  • Subject: Invoice(68-6414) -- Attachment name: 27-7813.pdf
  • Subject: Invoice(72-6353) -- Attachment name: 08-4031.pdf
  • Subject: Invoice(78-8672) -- Attachment name: 23-0458.pdf
  • Subject: Invoice(88-6908) -- Attachment name: 19-9273.pdf
  • Subject: Invoice(95-1750) -- Attachment name: 00-5523.pdf
  • Subject: Invoice(98-3753) -- Attachment name: 88-6908.pdf
  • Subject: Invoice(98-9897) -- Attachment name: 09-5337.pdf

The following are examples of spoofed email senders from Tuesday 2017-05-23:

The following are examples of SHA256 hashes for the PDF attachments from Tuesday 2017-05-23:

  • 0218178eec35acad7909a413d94d84ae3d465a6ea37e932093ec4c7a9b6a7394
  • 0a326eb9a416f039be104bb5f199b7f3442515f88bd5c7ad1492b1721c174b8e
  • 21da9eeded9581f6f032dea0f21b45aa096b0330ddacbb8a7a3942a2026cc8ca
  • 4458f43127bb514b19c45e086d48aba34bf31baf1793e3d0611897c2ff591843
  • 66320f4e85e3d6bd46cf00da43ca421e4d50c2218cb57238abb2fb93bef37311
  • 7dd248652f2b42f3e1ad828e686c8ba458b6bb5b06cea46606ceccdd6b6e823c
  • 8a474cdd4c03dd4a6ba6ad8945bf22f74f2f41830203f846d5437f02292bb037
  • 956e43ece563fd46e6995fae75a0015559f0a63af5059290a40c64b906be5b9b
  • 9beb67a68396375f14099055b712e22673c9a1d307a76125186127e289ab41a2
  • b2b9c02080ae6fbe1845c779e31b5f6014ec20db74d21bd9dd02c444a0d0dd9b
  • c126e731c1c43d52b52a44567de45796147aca1b331567ed706bf21b6be936b4
  • cde2ff070e86bc1d72642cb3a48299080395f1df554e948fd6e8522579dfe861
  • daf01a1f7e34e0d47ecdfcef5d27b2f7a8b096b4e6bc67fb805d4da59b932411
  • e477300e8f8954ee95451425035c7994b984d8bc1f77b4ccf2a982bb980806fe

The following are examples of SHA256 hashes and file names for the embedded word documents from Tuesday 2017-05-23:

  • 084ee31e69053e66fafe6e1c2a69ffec015f95801ce6020f7765c56d6f3c23ff - PQQIDNQM.docm
  • 0855061389b62ec6a9b95552357ff7571ae5c034b304978a533c6cba06c3f9e8 - GYTKPVM.docm
  • 1f2598dc7a7b8f84307d8c2fa41f5550c320f8192cd41e50b47570d3836e6fcc - RNJSMOVS.docm
  • 2dbf9e1c412aa1ffd32a91043642eb9cc80772c87dbbce3dd098c57d917277fb - DLDD7LH.docm
  • 3f95a7eeb1965193a4e92862c10897e04708b37b793b8e45f890d019358214c0 - DC2ZPQ.docm
  • 56cd249ff82e9bb96a73262090bc6a299ead64d6c75161520e745c2066f22430 - KAR6WLU.docm
  • 795d8312749c122fa10a93c9f3aa1c0f4ffc081714c0ddb66c141334f8ef0633 - M4SQLA2.docm
  • 8906d10a48487d8240bddd0c0cb5c076e88104c86bdf871b0143d74b6df3cc98 - NQBCXP4.docm
  • 91aa966e837c4144a1294aa912a2162397f3a6df98cf336891d234e267cd919f - RNOHLIAFU.docm
  • 933fcc1bf90716abf7c4eaf29b520d2276df895fb4dd5a76be2a55028a4da94e - PCHLUPL.docm
  • a98782bd10004bef221e58abcecc0de81747e97910b8bbaabfa0b6b30a93b66b - Q1DOEY13.docm
  • ae244ca170b6ddc285da0598d9e108713b738034119bae09eaa69b0c5d7635f8 - TH1DZZPT.docm
  • bc0b2fbe4225e544c6c9935171a7d6162bc611a82d0c6a5f3d62a3f5df71cf8c - OLZNKWSOW.docm
  • c702deaa2fe03f188a670d46401e7db71628e74b0e5e2718a19e2944282e05cd - VUG3FBFO.docm

The following is the sample of Jaff ransomware I saw on Tuesday 2017-05-23:

The following are URLs generated by malicious macros from the embedded Word documents. Theyre used to download the encoded Jaff ransomware binary:

  • billiginurlaub.com - GET /fgJds2U
  • david-faber.de - GET /fgJds2U
  • elateplaza.com - GET /fgJds2U
  • electron-trade.ru - GET /fgJds2U
  • fjjslyw.com - GET /fgJds2U
  • hr991.com - GET /fgJds2U
  • jinyuxuan.de - GET /fgJds2U
  • khaosoklake.com - GET /fgJds2U
  • minnessotaswordfishh.com - GET /af/fgJds2U
  • oliverkuo.com.au - GET /fgJds2U
  • pcflame.com.au - GET /fgJds2U
  • tdtuusula.com - GET /fgJds2U
  • williams-fitness.com - GET /fgJds2U

The following is post-infection traffic from my infected Windows host:

  • 185.109.147.122 port 80 - maximusstafastoriesticks.info - GET /a5/
  • rktazuzi7hbln7sy.onion (tor domain for the decryption instructions)

Final words

Much of this malspam is easy to spot among the daily deluge of spam most organizations receive. However, this PDF attachment/embedded Word doc scheme is likely an attempt to bypass spam filtering.

As always, if your organization follows best security practices, youre not likely to get infected. For example, software restriction policies that deny binary execution in certain Windows directories can easily stop this infection chain. Even without software restriction policies, the intended victim receives warnings from both Adobe reader and Microsoft Word during the infection process.

So why do we continue to see this malspam on a near-daily basis? I suppose as long as its profitable for the criminals behind it, well continue to see this type of malspam. If anyone knows someone whos been infected with Jaff ransomware, feel free to share your story in the comments section.

Emails, malware samples, and pcaps associated with the 2017-05-23 Jaff ransomware malspam can be found here.

---
Brad Duncan
brad [at] malware-traffic-analysis.net

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